Correctly classified, film posters are printed ephemera - throw-away scraps of everyday life. In the Thirties, the golden age of poster art, cinema managers paid 35c for them, displayed them for a week, and chucked them out.
At the root of dollar-driven film poster mania is the coming of the millennium. Matthew Schapiro, the curator of an investor-backed archive in Glastonbury, Connecticut, reputed to contain a hundred dollars 100,000 film posters, says: 'Come the year 2000, film will be seen as the artistic medium that has made most impact on 20th century culture, not just in America but throughout the world.'
For countless emigrants to America the nickelodeons of the Twenties and Thirties provided easily digested fare from which they absorbed the New World's ways. The early film moguls - Fox, Warner, Zukor - were emigrants themselves. They fed their audiences a hot-pot of romance, thrills and swank, lightly garnished with good taste. Paramount ran prestige advertisements during the Twenties, claiming that it was 'keeping the family together' while at the same time promoting titles such as Lady of the Harem.
Poster style - big, dramatic figures, garish colouring - was designed to put bums on seats. Charles Schlaifer, 20th Century Fox's advertising manager in the Forties, experimented in one town with an innovative and tasteful, but unsexy Betty Grable poster. It was a disaster. 'After that,' he said, 'we destroyed everything and went back to tits, legs and ass.'
Mr Schapiro is keeping out of sight of visitors his advance 'teaser' poster for one of the grand-daddies of horror movies, Boris Karloff's Frankenstein (1931) - a quarter million bucks' worth of Andy Warhol-style American culture. All will be revealed when he publishes illustrated books of his archive in the run-up to the year 2000. Meanwhile, he lets it be known that the poster has no credits, just a monster's face and the inscription: 'Warning] The monster is loose]'
Worthier cultural icons include Fritz Lang's Metropolis (1926), another quarter million-dollar blockbuster of which only two copies are known - in the Museum of Modern Art, New York, and in an American private collection.
Speculative boom-and-bust is the bane of people who collect for fun. When the price of a collectable spirals beyond their pockets they are likely to dump their collections back on to the market, busting it. It happened to coins in 1982 and it seemed to be happening to film posters in America in the seven years from 1981 to 1988. Middle-aged collectors who had begged surplus posters for a few cents from the warehouses of the National Screen Service, designer and distributor of posters, were grateful to get dollars 20,000 or so for their collections. But instead of glutting, the market absorbed the lot and prices continued to rise.
Today, more than 95 per cent of film posters can still be bought for less than dollars 1,000. But American speculators remain bullish. They believe that rare posters are still underpriced in relation to comparable American collectables - baseball cards which have yielded dollars 451,000 at auction, animation cels dollars 286,000 and comic book art dollars 75,000.
Such treasures are considered rare if 50 or 100 of a kind are known. But no posters are known for perhaps 75 per cent of films made before 1945 and 90 per cent before 1935. Whoever discovers in his attic a poster for Steamboat Willie, Mickey Mouse's first talkie (1929), will be able to retire for life.
The 'cross-over' factor has boosted the market by luring half-a-dozen other collectors' markets into it. Film posters appeal equally to home decorators and speculators. Pete Merolo, proprietor of the 500-seat M J 's Supper Club, on Staten Island, New York, has lined his restaurant's walls with vintage Disney posters and reckons that his top 20 are worth dollars 60,000-dollars 100,000 each. He paid dollars 75,000 for a Mickey Mouse Alpine Climbers (1936) and dollars 100,000 in a part-cash, part-exchange deal for another Mickey Mouse, the Frankenstein sequel The Mad Doctor (1933).
No collection of horror, science fiction, Westerns or memorabilia of Thirties vamps is complete without crossing over into film posters. Dana Hawkes, director of Sotheby's collectables department in New York, adds that collectors of baseball cards, comic art and Disney animation cels, in search of something new, have also started bidding for them. 'It has all the energy of a fresh new market,' she says.
Cognoscenti can source film poster style to early Wild West show and circus lithography, and reel off the names of pioneer artists such as Jules Cheret, who fathered the genre in 1890. But when it comes to price, it is the film title and the star's name that counts most - exactly the same factors that put bums on seats in the first place.
Horror and animation art are the biggest attractions, which explains the high cross-over value of Mr Merolo's Mickey Mouse Frankenstein. A big, three-sheet poster of King Kong (1933) fetched pounds 57,200 at Christie's New York in December 1991, an auction record for a film poster which lasted 18 months.
As for stars: 'in' are Bette Davis, Errol Flynn, Humphrey Bogart and James Cagney. 'Out' are more recent names: Audrey Hepburn, Grace Kelly and Elvis Presley. The only Presley of significant value, Jailhouse Rock (1956), is worth just dollars 500-dollars 750. You can pick up a run- of-the mill late Presley for dollars 35. Hepburn's Breakfast at Tiffany's (1961) can make dollars 800 but her prices go as low as dollars 50. Kelly's High Society (1956) with Frank Sinatra and Bing Crosby is still worth only dollars 150.
The big auction houses came late into the film poster game, hiring collector-consultants to show them the way. But Christie's four New York sales since 1990 have all been 100 per cent sell-outs, raising nearly dollars 4m. The record auction price for a film poster - dollars 77,000, paid in May - is held by neither Sotheby's nor Christie's, but by the relatively obscure Vintage Poster Art of Cleveland, Ohio. It was paid for Dracula (1931), starring Bela Lugosi, the first of the big Thirties horror movies. Only one other copy of the sepia poster is known.
Meanwhile, about a dozen small American auction houses are bumping up the number of their sales from one a year to three. More and more posters have been tempted into auction, with the result that, in the past year, middle- market prices have actually sagged. The Movie Poster Price Database in which John Kisch, a New York collector, publishes up to 20,000 private and auction transactions every January and August, shows that Bogart's classic Casablanca (1943) in standard one-sheet size sold at auction four times in January this year at prices ranging from a top dollars 5,500 to a bargain dollars 2,500. Back in 1991 the only copy to appear at auction fetched pounds 5,200.
Such erratic prices reveal an 'imperfect' market in which information about market values is a scarce commodity. The most expensive posters, hoarded in anticipation of even bigger prices, have yet to submit to the big auction houses' public information skills. The bulk of transactions, which include a bumper mail-order trade, are private - though scarcely less hyped. A network of up to 10,000 of them communicates across America by telephone and fax. Telephone bills of dollars 500 a month are not uncommon - hardly a bank-breaker for the East Coast collector who last year parted with dollars 80,000 for Boris Karloff's The Mummy (1932), the highest cash price on record.
This December Christie's fifth sale, on the 13th, will be pitched against Sotheby's second sale only five days later. Both houses gleefully leak information about their top-priced lots, confident that the chances of both houses having a copy of the same money-spinner are slim. Christie's is trumpeting its one-sheet Charlie Chaplin The Gold Rush (1925), estimated at dollars 30,000-dollars 40,000.
The world's biggest collector of Chaplin film posters, Andrew Cohen, the Londoner who rescued Betterware, the British door-to-door household goods company, told me he was prepared to pay dollars 50,000 or more for it. He expected competition from two or three other bidders. 'This is the most collectable Chaplin,' he said 'and is going to fetch the highest Chaplin price. I know, because I'm prepared to make sure that happens.'
He has a reputation for spotting opportunities. In June he raised pounds 30m by selling 13 per cent of his and his parents' stake in Betterware. He said of film posters: 'It is a strong market which started in recession and grew in recession. When it comes out of the recession it's going to boom.'
Chaplin posters collected over the past four years and displayed in his mansion include City Lights (1931), one of only three known, for which he paid dollars 35,000 in a private deal. He paid dollars 32,000 for The Kid (1921) at Christie's New York last year.
The consignor to Christie's New York of the one-sheet The Gold Rush is Bruce Hershenson of West Plains, Missouri, Christie's own consultant in film posters. Not averse to creating a gold rush in modern times, he told me: 'If he (Mr Cohen) doesn't get this one he may never get another opportunity. For 25 years nobody had seen a copy. Even now only two are known. The other has Chaplin's moustache cut out.'
Mr Cohen is a rare bird, one of only five serious British collectors. His auction bids in New York are made for him by two British collector-dealers, Tony Nourmand, a maker of short animation films, and Bruce Marchant, a sculptor. They are the only Brits who regularly venture across the Atlantic to buy.
Transit of American buyers in the opposite direction is rare although the successful sale of over 240 film posters in the Kobal collection at Christie's South Kensington last December did attract America's biggest dealer, Jose Ma. Carpio of San Francisco. He paid the auction's top price of pounds 7,260 for seven 'black cinema' lobby cards for Hallelujah] (1929), which had an all-black cast and was shown in segregated cinemas in the United States.
Mr Kisch of the Movie Poster Price Database has the biggest collection of black cinema posters. He is sending 200 of them for display at the National Film Theatre's season of black cinema in London in February. They may do something to shift British taste in posters towards Hollywood. To the British, posters have hitherto meant Toulouse Lautrec, Mucha and British Railways. The record auction price for a British poster is pounds 68,200, paid at Christie's South Kensington in February for an 1895 Charles Rennie Mackintosh of an Art Nouveau female figure. Hardly a King Kong - but at least the price was right.
The next general poster sale will be at Christie's South Kensington on 1 October. A useful book is 'Reel Art' by Stephen Rebello & Richard Allen (Abbeville Press, New York, 1988).