TToday, when a $100,000 house sounds as though it's a bargain, everybody needs all the help they can get. Currently, authors and publishers are doing their best to earn their own down payments by selling you books on how to live well though broke.

"House & Garden's Book of Remodeling" (a Studio Book by The Viking Press) was planned by Mary Jane Pool, edited by Will Mehlhorn, designed by Miki Denhof and written by Beverly Russell. They did a good job. It's easily the most beautiful (lavish color photographs) and interesting how-to-do-it book in this season's crop. The book deals with 55 case histories. Obviously none are for your loving-hands-at-home remodelers. These took money and top professional design and work. But the ideas they suggest are the best.

For Washington readers, there is particular interest in the often published house by architect Warren Cox, and the Edward Burling and Robert Eichholtz houses by Hugh Newell Jacobsen, all in Washington.

There are other marvels. A loft in New York is one enormous room designed by Mark Hampton. A firehouse in San Francisco was redesigned by John Dickinson with what must be one of the most magnificent art noveau tables ever, not to mention a closet wall that looks like a street scene. A greenhouse kitchen by architect Adolf DeRoy Mark is a tour de force of bricks, stuccoed arches and a spiral staircase. There's a whole section on remodeling barns.

"How to Buy a Home at a Reasonable Price," by Robert Irwin (McGraw-Hill, 246 pages, $12.50), is written by a California real estate broker and editor. The book winds its way through such dragons and dungeons as FHA, VA and variable rate mortgages of single-family houses, mobile homes, condominiums, domes, prefabs and a few other arcane matters. The best parts of the books are those dealing with financing and real-estate practices.

"The New Complete Book of Home Remodeling, Improvement and Repair," by A. M. Watkins (Charles Scribner's Sons, $15.95). This practical book is an excellent text. Watkins starts at the beginning -- "when is a house worth remodeling?" -- and works his way through the possibilities.

He makes many good points. Basements are seldom worth remodeling unless they are dry and have good light. The remodeling market is full of cheats waiting to take your money. (Watkins tells about one man who brings a bottle of termites with him to scare the homeowner.) In any major job, an architect is a necessary ally. And every remodeling should consider passive solar heat, insulation and innovative ways to heat.

"Don't Move -- Improve" by Cle Kinney and Barry Roberts (Thomas Y. Crowell, Publishers, $14.95) is full of good ideas and interesting (though black and white) photographs. The gee-whiz style is rather tiring. But if you can wade through the mercifully brief text, you'll have some practical plans for your own remodeling.

After studying these tomes, you'll be prepared to start your own remodeling. Of they may discourage you so much, you'll switch your reading to science-fiction.