Bloomingdale's is so trendy that even its ads have ads.

For the first time, the Manhattan-based store chain's slick, four-color catalogue features equally slick and four-color advertisements for products ranging from Calvin Klein cologne to R. J. Reynolds cigarettes.

"Through the catalogue, we're able to target our customers in a very sophisticated manner so we can really deliver more bang for the buck," said Barry Marchessault, Bloomingdale's senior vice president for direct marketing, who oversees the store's $60 million mail-order business. More than 1.6 million copies of the fall catalogue have been sent through the mail.

The ads make Bloomingdale's the first upscale cataloguer to carry ads and hints at what several consultants predict soon will become a common feature of the multibillion-dollar direct-mail catalogue industry.

"What you're seeing is a pioneering effort that will quickly become a trend in catalogue marketing," asserted Jo Von Tucker, a catalogue marketing consultant. "Catalogues are competing for attention in an overly crowded mailbox, so we have to find ways to make catalogues work more effectively."

"We look at it as a new type of print media," said John Chunko, vice president of Catalog Media Corp., a one-year-old New Jersey company that sells advertising for catalogues. "Catalogues have only one real revenue stream -- the sale of merchandise. But for all intents and purposes, catalogue publishers are really publishing a magazine. It's a magazine that talks about buying merchandise; the catalogue products and descriptions are the editorial."

The result is what media consultants are now calling "magalogues" or "catazines": print hybrids that try to blend catalogues and magazines into a potentially more profitable mixture.

Chunko, whose company is working with the San Francisco-based Sharper Image catalogue, predicts that over a five-year period, a catalogue with a 1 million circulation distributed six times a year could earn upwards of $5 million in profits with the appropriate advertising base.

He fully expects Sharper Image, a high-tech catalogue targeted to a male audience with an average of 2.5 million catalogues mailed out a month, will gross millions when its advertising begins early next year. A full-page ad in the Sharper Image catalogue will cost advertisers $65,000.

"We offer targeting that is much tighter than the more traditional magazines," asserted Chunko, but he emphasized that catalogue publishers have to be sure to pick the right advertiser to fit the catalogue's image.

"Realistically, Bloomingdale's should easily make $2 million or $3 million" from its catalogue advertising, said Milton B. Kaplan, president of Catalogue Advertising Sales Ltd. "Lincoln Continental, Christian Dior, R. J. Reynolds . . . this is their audience."

Kaplan says that national advertisers, impressed with the Bloomingdale's name and the barrage of statistics illustrating the direct-mail success of the catalogue, are snapping up the pages. Catalogue Advertising has sold more than 70 of its allotted 100 available pages for the next 12 issues of the catalogue.

Other retailers are less impressed with the potential of catalogue advertising. "We've made the decision not to accept third-party advertising," said Bill Williams, senior vice president of direct mail at Neiman-Marcus, the fashionable Dallas-based retailer