Personally I would always go for stainless steel: they are cheaper, more discreet and far less nickable then gold. To get anything good, look at starting at pounds 200. Second-hand watches represent great value. For example, in the Seventies Omega made a watch for the Apollo space crew, known as the "Man on the Moon"; these can be picked up for around pounds 500. The same watch has been reissued and sells new for pounds 1,400. I know I'd prefer the original. There's no stigma in second-hand: the maitre d', as he checks your wrist and gives you a good table, is not going to know. Watches keep their price: something good and rare will always have a resale value, sometimes above what you paid for it. If you buy new, as you walk out the shop it will lose at least a third of its value. And that is if it has a proper movement; if it's quartz, then the resale value is hardly worth bothering with.
As with any other commodity, the price of watches fluctuates with fashion. The current market favourite is the chunky, black-faced diver's Rolex known as the "Submariner", available at about pounds 1,200; new price pounds 2,070. In fact, diver's, yachter's and driver's watches from the Seventies are much in vogue. So much so that Tag Heuer, formerly just Heuer, are planning to reissue Steve McQueen's favourite, the "Carrera". No price yet, but second-hand they are available for around a grand. The gnomes of Switzerland have at last woken up to the fact that there is a market outside the Gulf, and the reissue of old models is all the rage. The classic Jaeger-Le-Coutre, known as the "reverso", because this oblong baby has a face on both sides, is another to see the light of day again. Current price in stainless steel pounds 2,154, about pounds 1,200 used.
It's best to be clear about what you want before parting with the folding. Most independent jewellers sell old watches and they usually come with a guarantee; however, it is the dealers who are most likely to get what you really want. Track them down at Antiquarius and Chenil Galleries on the King's Road in Chelsea, the arcades of Portobello market (Saturdays only) and the shopfronts in Hatton Garden and Clerkenwell Road. All in London, sadly. And, finally, condition and working order are everything with watches, so only bother with the best. Good Luck
Picture above: Heuer Monaco as worn by Steve McQueen in the 1968 film `Le Mans'; current second-hand value, pounds 700.