Want to go to London and on to Paris for under $25? How about London to Athens for $85, London-Amsterdam for $27, London-Copenhagen for $70? Well, then, welcome to the world of Magic -- the Magic Bus, of course.

On the other hand, if you'd prefer to fly, maybe you should see Riaz Dooley. He bounces around among three or four London offices, telephones growing out of both ears, talking deals of up to 60 percent off some big-name airlines' regular tickets.

Then there's Trailfinders. Inshallah, they'll route you on an el cheapo "Great African Adventure," London-Cairo-Nairobi, via whatever in the way of public transport is moving, some of it maybe just barely.

International travelers don't have to go to London to set themselves up in cheap deals but, no doubt about it, that's where you'll find a barrelful. Over the past decade, the British capital has turned itself into the world's foremost travel bazaar, specializing in everything from the weird to the wonderful.

"I think it really started back in the psychedelic days," says a peripatetic Austrailian who's become an eagle-eyed comparison shopper. "Everybody and their cousins descended on London and, after a while, rather naturally started peering around for a cheap way to get somewhere else."

"Somewhere else" in the late '60s was India. So Greg Williams, a Briton, bought himself an old bus and recruited a load of like-minded passengers who also wanted to head east. But first he applied some paint and turned the bus into a spectacle that struck some observers dumb. One stayed calm enough to say, "That's magic!" and thus a great name was born.

Slowly but surely, Williams built a company to go with the name and began "scheduled" service between Europe and the subcontinent. It was of course, the flaky way to go. On one trip a driver reportedly fell in love with one of the passengers and refunded everyone else's ticket cost so he could terminate the trip and attend to private business.

On another occasion, according to a still-satisfied customer's story, the bus's windshield was blown out as passengers and crew tooled through the Alps, but they plunged on to Athens before having it fixed. At some borders, authorities -- not without reason -- have suspected dopers were aboard and brought dogs around for a sniff or ripped up a seat or two.

But now even the Majic Bus had enough magic to keep going to India after Iran blew up. The events in Afghanistan merely added a final fillip. Even so, with sky-high intra-European air fares, Williams found he still had plenty of clients between London and European cities, especially if he continued to undercut virtually every other kind of transport.

So now there's service to Dublin (12 pounds one way, about $27) as well as the other places mentioned. There's also the five-beds-to-a-room Magic Inn in Amsterdam.

The biggest change, though, is probably in equipment. The magic Bus now proudly contracts for "brand-new, modern buses, properly registered and insured," says Ramon Rebel, who runs the company's U.S. ticket office -- selling seats at slightly higher than London prices -- in Van Nuys, Calif.: phone (213) 994-0329. And with the shorter trips, he says, they're also attracting "quite a few" over-30s and bargain-hunting nondopers.

Bargain hunters of all ages and descriptions descend as well on the Youth Hostel Association's travel office near London's Covent Garden, Employes there save a lot of words by chalking up current air-travel prices on a blackboard and distributing mimeographed information sheets. They also sell to the public, not just to hostel members, and many of their recent air-ticket price quotes have been in the same ballpark as Riaz Dooley's.

Dooley, a Pakistani by origin, is currently dancing in the London limelight. He's the bucket-shop proprietor who's trying to bring bucket shops -- agencies that sell air tickets at less than "legal" prices -- out of the closet. At present, the image is of shady dealers operating hugger-mugger fashion with come-on ads in classified sections, and there are indeed more than a few ripoff artists.

Purchasers of under-the-counter tickets, though, aren't doing anything illegal; it's the sellers who are liable to prosecution. Dooley wants to legalize discounting and to offer to customers the same stability and financial guarantees as travel agents with proper airline appointments. Determined to let it all hang out, he's mounted a publicity campaign, formed an association and even opened a travel agency near Portobello Road at 221 Westbourne Park.

Bucket shops came even more into the sunlight when top executives of British Airways recently acknowledged on British television that BA tickets have been sold at discount through bucket shops. While hardly hot news in the industry, the admission did let the public-at-large in on the fact that air fares are no longer written in permanent ink. Not surprisingly, accredited British travel agents who still have to sell at published rates are boiling over in frustration.

Of course, bucket-shop prices also vary. You're likely to find lower prices in one place than another, sometimes reflecting volume business with a certain airline, sometimes merely different markups.

By the same token, Saintseal, a charter operator, frequently has lower prices between Britain and Italy than anyone else. German Tourist Facilities is another name for comparison-shoppers to remember. And perhaps the only way to know you've reached rock bottom is to calculate that anything more than 60 percent off the major airlines' economy-coach fares is highly unlikely.

To travel-shop in London, it's also useful to know about specialists like Trailfinders and WEXAS. These two sell air tickets, but also offer low-budget "expedition"-type travel arrangements, in effect walks on the wilder side in places like Yemen. Additionally there are tour operators like Tjaereborg, who sell low-priced packages by cutting out travel agents and going directly to the public, as well as to agencies with special deals for late shoppers (looking for buy-today, go-tomorrow package tours) and for "students."

Of course, not all deals are as good as they sound, and in the end, London's travel bazaar is emphatically a part of the "buyer beware" world.

Although the suppliers aren't concentrated in one area as they are in London, a sophisticated shopper who's willing to do the same amount of work can frequently make out just as well in the United States. The trouble is, you never know for sure until you look, and change -- here and there -- is definitely the name of the travel game.