So why, I asked myself as the train looped around the magnificent arc of viaduct before unravelling into Inverness, was I spending slightly more than that amount for six days on an old barge in Scotland?
Yet by the end of the week, I would defy anyone to nominate a cruise that offers better value than Fingal of Caledonia. This unusual turn of generosity was all the more remarkable because I had failed to benefit from a single horse-power of the diesel engine that helps the Flemish barge shuttle between Inverness and Fort William.
Every Saturday throughout the summer (which the crew optimistically defines as from now until mid-October), Fingal climbs the flight of locks at each end of the Caledonian Canal. A lanky, well-heeled lass, her 128 feet have been turned into comfortable cabins for a dozen guests, and slightly-less-comfortable ones for half-a-dozen crew. Paying guests and paid hands meet in the middle, at a generously provisioned galley.
That there are unlimited quantities of hearty food is crucial, because you are not here to enjoy yourself by lounging around on deck. The crew will see to that: they are young, gifted and back for another season of showing holidaymakers how to make the most of Scotland's great divide.
With Fingal tethered at the bank of Thomas Telford's masterpiece, passengers are plied with thick porridge and industrial quantities of tea. Then they are told where to get off. Clients are encouraged to cover the startling terrain of the Great Glen in a variety of ways. Don't think you have to bring your own canoe or cycle; hidden in the gunwales is enough equipment to launch an activity centre, which is what the vessel turns out to be.
So instead of waiting for Fingal to squeeze up the flight of locks from her mooring at Inverness, you can borrow a mountain bike to tackle the gentle rise up to Loch Ness. The town quickly retreats in the face of an invasion by the massed ranks of green: dark, tall firs holding command over ranks of pale fern and verdant grass. The river Ness cuts through the forest, and occasionally skirmishes with the canal and a handy cycle path that deposits you at one end of Britain's deepest, darkest and most celebrated body of water.
Loch Ness is scary, at least from the A82. The monstrous twists and turns of a road overpopulated by tourist coaches and caravans make the journey along the north shore miserable. Luckily, the Fingal crew offer plenty of alternatives, such as windsurfing across the steely waters, your wake leaving an alien ripple on the surface as you pass the ghostly remains of Urquhart Castle.
The halfway point is the curiously jumbled town of Fort Augustus. The name indicates its military origin at the crossroads of General Wade's military roads, and prime site for an army camp. His HQ became an abbey, which later metamorphosed into a tourist attraction of the "things to do when it's been raining all week" variety (together with the website www.monk.co.uk). But it closed at the end of last year, and there are rumours that it will become a luxury golf resort.
Telford's aquatic highway clambers straight through the ensemble. A ladder of locks lifts Fingal to the highest point in the Great Glen - around 100 feet above sea level.
A hike organised by the crew takes you much higher than this, crunching up through the hillsides beaten down by too much weather. Every now and again the mist pauses for a breath of clear air, revealing vistas that are enough to make you weep at the sheer beauty, and tragedy, of the Highlands. Afterwards you can go and have a nice cup of tea at a waterside cafe while Fingal catches up.
You can practice solitude as easily as bonhomie. A testing, yet fantastically rewarding, solo bicycle ride takes you on a perpendicular excursion towards the Western Isles. From the craggy scar of the Great Glen, the landscape subsides into a vision of serenity that is as magical in its scale as in the exquisite detail of every tiny brook and flourish of heather.
Magic prevails, too, at the Falls of Foyers, one of Scotland's original tourist attractions, and a natural, and brilliant, optical illusion. A spectacular waterfall hurtles down an almost sheer, broad rockface, the momentum of the water mesmerising the onlooker. Stare at it for a few seconds, then look at the adjacent cliff. You will see it rising as clear as an elevator. Who needs cinemas when you've got Foyers?
Later that day, what starts as an innocuous canoe trip may turn into the highlight of the holiday. You drift inshore from Fingal's mooring on the loch, then turn upstream towards the falls. You paddle tentatively, fearing a kind of Niagara-style deluge at any moment. After a spot of portage - coaxing the fibre-glass vessel across some obstinate rocks - you find yourself at a deep pool near the foot of the falls. You can tell that it's deep because Davy instructs you to climb a high ledge and leap in. Then you slalom down the rapids on your back - raftless whitewater rafting.
By Thursday, Davy and I were holding hands. This was not any kind of shipboard romance, you understand, but because we were on a jaunt that involved bagging two Munroes. The pair of 3,000-foot peaks is linked by what I now know is termed a "knife-edge ridge".
That second bowl of porridge at breakfast will prove a wise nutritional investment on a long, punishing scramble to Sron a Choire Ghairbh, a peak from where half the country seems visible. The particular bit of Scotland that concerned me, though, was that ridge. Halfway along the blade, I looked across to Loch Lochy - where Fingal was cheerily steaming - and down to a scree that suddenly seemed horribly vertical. Davy hauled me away from what I shall unconvincingly describe as "danger", up to the cairn that certified success in scaling Meall na Teanga, and then on a hilarious tumble through the prehistoric debris to the shore of the loch. Fingal was waiting with a reassuring wisp of vapour emerging from the galley.
Before a table-sagging final dinner that proved as superlative in quality as quantity, Davy felt it necessary to find a bridge overhanging the water and to invite participants to leap from it into water that looked as gloomy as I had done on the ridge. Should you be tempted to take the plunge, bear in mind that Loch Lochy is nearer to the North Pole than is either Moscow or Juneau, state capital of Alaska. Then savour a moment of exhilaration that is so intense as to be priceless.
Simon Calder paid pounds 425 for a week on `Fingal of Caledonia' (01397 772167). He paid pounds 74 return to fly from London City to Edinburgh on KLM UK (0990 074 074) and pounds 21 on ScotRail (0345 550033) for an Apex return from Edinburgh to Inverness