I am economist Robert Frank's nightmare. I am the consumer who has taken the time-honored American sport of "keeping up with the Joneses" and turned it into "keeping up with the Gateses"--the Bill Gateses. And I've found a new practice field: the new Expo Design Center in Fairfax, where I have an appointment a week before its official opening this Thursday.

My mission: to assemble a $50,000 or $60,000 fantasy bathroom, something beyond my means but not beyond my imagination--and decidedly not beyond the possibilities at Expo, the spiffy new offspring of Home Depot Inc., a company that knows a little bit about putting the merchandise out there and then just standing back from the stampede.

Expo blends the concept of the high-end kitchen and bath showroom with the idea of the warehouse store: yards and yards of kitchen and bath setups; a maze of tile and marble displays to wander through; alcoves ablaze with chandeliers and sconces; an entire wall of kitchen sinks; a dozen built-in refrigerators and pro-style ranges. I won't need a decorator to get inside this showroom; I will need deep-ish pockets to walk away with more than a decorative candle or two.

But my exercise is a fantasy, so it's with visions of steam cabinets and hand-painted sinks and non-fogging mirrors that I approach Expo project designer Kelly Crawford, who has been a decorator for model homes, and bath specialist Buddy McMahon, previously an independent plumbing contractor.

In an earlier chat with Expo's vice president for merchandising, Steve Smith, I've been assured it would be easy to rack up a $100,000 bill for a master bath were I to succumb to custom-made tiles and custom cabinetry in furniture-grade woods. But, as I tell Crawford and McMahon, I'd rather spend my fantasy money on those fabulous doodads I keep seeing in fancy decorating magazines.

Crawford wants to explain the painstaking process through which she would lead a real customer--the estimates, the lifestyle questions, the design retainer that will be charged against eventual purchases--but I just want to shop.

The size of this mythical bathroom? Oh, let's say we're converting a small bedroom; let's call it 11 1/2 by 12 feet with a bump-out to hold my first "purchase," a two-person whirlpool tub from Aquatic Industries Inc. I could settle for a one-person Seacliff tub from Aquatic's Value series, $881 at Expo, but the Millennium V, with its pillows and eight hydrotherapy jets, will soothe two people for $5,729.50, which is 30 percent off the manufacturer's list price of $8,185.

Now, I love to spend money on luxuries and hate to waste it on necessities. So I'm perfectly willing to pay $331.80 extra for an upgraded three-speed pump for the tub and $150.50 for an extra hand-held jet with spin nozzle. And Dolphin's Deluxe Split-Finish Chrome Roman Tub Fill Spout, at $795.27, will allow the tub to fill with an elegant "sheet" of water. But then McMahon points out that the 92-gallon tub will take forever to fill unless my standard half-inch water pipes are replaced with three-quarter-inchers. Bingo! Maybe an extra $2,000 in plumbing costs. Luxury has its own necessities, I guess.

But wait! Where is this white acrylic extravaganza going to nestle? What kind of look will the bathroom have? A quick stroll over to the tile kiosks presents the endless possibilities--endless because I can have the pattern from my favorite Hermes scarf painted on the wall tiles if I want. Do I want the soothing sandy tones of tumbled marble for a "Tuscan Sun" look? Sleek pewter-glaze tiles? A Greek-ruin look with mosaic tiles from the Ann Sacks Collection? Those goofy photo-reproduction tiles (you can shower with "grass" or "stones" underfoot)?

If this were a real bathroom, those decisions could take me a week. As it is, Crawford, McMahon and I pick out flooring and wall tiles in less time than it takes some people to choose a movie to rent.

The verdict? Clean! Clean is always good in a bathroom, so we go with $8,430 worth of white Thassos marble tiles for the floor and walls up to chair-rail height, where we'll cap it with a nice Mediterranean-looking frieze of cool-looking sea-blue and -green one-inch glass mosaic tiles. The same glass tiles will reappear at intervals across the floor. Applied against white mastic, they will glow from the walls. And from the shower room.

Oh, yes. I haven't yet mentioned that my personal definition of luxury is a little alcove arrayed with nozzles and wands and sprays and "rainbars." Walk in and get drenched, up, down and sideways. No battle with a nasty shower curtain, no tripping over the edge of a tub I never use. Room to bend over, stretch, sit down. Then, with one touch of a dial, leave the rain forest behind.

I can have enough gleaming chrome waterworks for two people, Crawford and McMahon later tell me, for $5,000 (okay, it's $4,997.04). Construction of the 5-by-5-foot alcove could be another $3,000 or $4,000. The marble tiles for the tub deck and shower walls: $3,250. Add a full-length $243 glass door and a $1,350 Steamaster steam unit and the bathroom becomes a spa.

When I emerge from my private little rain cloud, I'll be able to proceed with fixing hair and makeup without delay because the bathroom mirrors will be fog-free. That's right: The two cobalt-blue-edged Robern medicine cabinets ($682.50 each) that hang above the "Glacier" frosted-glass sinks from Porcher ($4,492.50 for both--what a bargain!) are electrified, so they will never fog up from all my waterside activities.

It's now been four hours since I arrived at Expo. McMahon keeps thinking of decisions we haven't made yet ("What about the faucets for the sink?" "Did we decide to get a bidet?"). Crawford points out there's no toilet in this bathroom yet. I tell her I'm tired, just throw in a white one and, yes, a matching bidet.

The next day Crawford faxes me a dandy little sketch of our handiwork. She has added a tall chrome-and-frosted-glass cabinet and shelves for $658.22. Nice touch. The total of all the bits and pieces: $39,079.88. McMahon does a rough estimate for all the demolition and construction labor: $22,000, give or take. Grand total: $61,079.88.

The payoff? Because it's a fantasy I don't have to pay for it--or wait until they find a contractor who can find time for this "modest" job.

CAPTION: This Hansgrohe hand-held shower set will run you $219.04.