NEW YORK -- Pssst, wanna buy the Brooklyn Bridge? How about a concrete slab in a garage? A pool of water in Long Island Sound?

Anthony Scozzafava of Leonia, N.J., a real estate man, didn't buy the bridge -- who would fall for that cliche about suckers in New York? -- or the parking space.

But he did buy the water.

''I felt as though I was being ripped off,'' Scozzafava said, mostly in jest, as he stood aboard his 42-foot yacht docked in his 42-foot-long pool of water -- a so-called ''dockominium'' at a City Island marina, north of Manhattan, for which he plunked down a cool $49,000.

In this city where people pay millions of dollars for apartments and where a recent study found housing prices to be the highest in the country at a median of $183,000 for a single-family home, the latest accessory for the very well-heeled is a dock or garage condominium.

In Brooklyn, real estate entrepreneur Howard Pronsky is selling concrete slabs -- 7 feet by 14 -- inside a building for about $30,000 apiece and calling them garage condominiums.

People like Peter Ornstein, who doesn't even own a car, are buying them -- in his case, for investment.

''I was going to buy a co-op apartment and rent it out, but this way I never have to worry about the tenants telling me the roof fell in at 3 a.m.,'' said Ornstein, an art dealer.

Ornstein didn't get a lot of space for his money, even by New York standards, but at least his investment stands on solid ground.

The same can't be said for Scozzafava's, on the waterfront at City Island, a marina enclave north of Manhattan. But he got other fringe benefits.

Jack Hammel, vice president of sales at Minneford's Marina, is quick to point them out when he walks people through the city's only dockominium.

The dock is brand new, consisting of more than $1 million in new timber. A metal conduit running through its center contains all the services modern mariners have come to expect: running water, electricity, telephone lines, even cable television.

''We walk them down ... and let them feel the marina,'' said Hammel, explaining the sales pitch that in less than two years has sold all 284 of the slips.

''We invite them to spend the night for free to see how they like it, and most of them never want to leave. They get a feel for the place and never want to go home.''

Hammel said banks were skeptical about providing financing, but eventually came around.

''We told them a man would give up his home, his children, his wife, before he gives up his boat,'' Hammel said. ''That's their major toy in life.''

But even Hammel, who paid $17,000 for his first house in 1952, admits he would have found the prospect of people paying $50,000 or more for a boat slip ''incredible'' a few years ago.

''No way,'' he said. ''It's like taking a trip to the moon.''

Pronsky said his garage condominium seems less oddball today than it did when it opened a year ago.

''People are guaranteeing themselves a place to park, and with the average car costing $20,000, they don't want to leave it on the street and worry if it will be there in one piece tomorrow,'' he said.

Besides, he said, parking spaces on the street are scarce, some buildings that formerly were garages have been converted to housing, and no new garages are being built.

Pronsky said 83 of the 145 spaces were sold in a little more than a year since the garage opened, with some people buying two or three as an investment