Netti Schreiner-Yantis' 1,000-page genealogical catalog is not something you'd choose for bedtime reading, but at $15 a copy--with sales expected to reach at least 20,000 for the third edition--it has become a profitable enterprise for her.

The past president of the National Genealogical Society has aimed her guide, Genealogical & Local History Books in Print, at the thousands of Americans interested in tracing family histories. More than 10,000 books about communities and families throughout the country are listed.

"In genealogical publishing," she says, "everybody has to be a self-publisher. Nobody can make money on the history of their family. You might have a ready market for 500 books if you go into eighth and ninth cousins."

A one-time home economist who ran her own business cleaning home air filters, Schreiner-Yantis, 52, of Springfield, has counted on the enthusiasm of "Roots" hobbiests to sell a large percentage of the books directly by mail. (And she doesn't have to split the profits with bookstores and distributors.)

As another cost-cutting step, she and a secretary type the book on an IBM print-like typewriter, eliminating the substantial cost of a typesetter for such a thick volumne. Operating out of her home cuts down on office overhead.

A recent press run of 5,000 copies cost about $18,000. By direct mail, these books could bring in about $80,000 before expenses (1,000 hardbound copies will sell for $20). With that kind of return--"at this point," she says, "I make a decent profit"--she has turned the cleaning business over to her son.

Schreiner-Yantis has a mailing list of 30,000 potential customers, and she advertises in genealogical journals. She also looks for "free advertising" in book reviews and mention of her book in genealogical articles in newspapers and magazines.

She considers herself "lucky" that she managed to get into a national bookstore chain with hundreds of outlets, the result of a trip to the Springfield Mall after the first edition of her book came out. One bookstore was "uninterested," but the manager of B. Dalton's told her, "Well, you're a local author. We'll put it right next to the cash register."

She quickly sold 150 copies and soon was shipping books off to other B. Dalton stores. Her publishing house bears the same name as her book. When she applied for an International Standard Book Number (ISBN), she was told her company needed a name. "I didn't have one, so I used the name of the book."

The first edition took her three years to compile; the latest, which came out in 1981, about a year. A fourth edition is under way for 1984. She also is a publishing consultant to first-timers and is completing a how-to manual, Publish It Yourself, for which she already has orders.

Meanwhile, she has just published a book someone else wrote. It's another 1,000-pager that probably won't end up on your nightstand either: Index to the First 20 Volumes of Virginia Genealogy.