The main advantage of holiday shopping from mail-order catalogues--millions of people have discovered--is that it can be accomplished any time, without leaving home. And often, you don't even have to send off a letter, but can pick up the phone and order toll-free.

Catalogue-shopping has come a long way from the days when Sears, Roebuck and Montgomery Ward had the corner on the "wish-book" market. The average family receives 40 catalogues a year, according to the Direct Mail/Marketing Association, and it's been predicted that by 1990 mail sales will account for one-fifth of all general merchandise sold in this country.

A bonus this year is that mail-order houses -- like some retail stores -- have a surplus of inventory, which means some spectacular pre-holiday bargains.

We set a $10 limit. Here's a sampling of gifts available at that price (postage not included, unless noted). Home Sweet Home

* Brass twisted braid-stemmed candle snuffer, 12 inches long, $10. Trifles (P.O. Box 344432, Dallas, Tex. 75262).

* Lillian Vernon's 10-piece tool set: 5 wooden tools, 2 giant forks and 3 whisks, in an earthenware pitcher, $6.98. Lillian Vernon (510 S. Fulton Ave., Mount Vernon, N.Y. 10550).

* Home-photo inventory that holds 90 photos of valuables and 1,000 associated entries (date of purchase, price), $8. Joan Cook (3200 S.E. 14th Ave., Fort Lauderdale, Fla. 33316).

* Frosted-glass bird swizzle sticks, 5 1/2 inches long. Set of 6, $10 postpaid. The Horchow Collection (P.O. Box 340257 Dallas, Tex. 75234).

* Special hammer with grooved and magnetized head so nails don't have to be held to be started, $9.98. New Hampton (340 Poplar St., Hanover, Pa. 17331).

* Work apron of heavy-duty white canvas, with 14 pockets (two large, 12 more of various sizes) and two leather hammer loops. Size-adjustable, washable, $7.05. Sporty's Tool Shop (Clermont County Airport, Batavia, Ohio 45103).

* Zinc sundial for your garden, 4 1/2-inch diamter, $9.30 postpaid. The Carolina Collection (2700 York Rd., Burlington, N.C. 27215). Home Sweet Office

* Black matte ball-point with 3 1/2-inch digital display of time and date, $9.90. Grand Finale (P.O. Box 345020, Farmers Branch, Tex. 75234; catalogue $2).

* Huge paper clip (18 1/2 x 4 1/2 inches), $10. From Think Big! (390 W. Broadway, New York, N.Y. 10012). Kits

* For the novice needleworker: Let's Get Started crochet or knit kit. Each kit has all the tools, equipment and instruction beginners need (except yarn). Each kit $7.99 from Herrschners, Inc. (Hoover Rd., Stevens Point, Wis. 54481).

* For a beginning woodworker, a magazine rack kit. Finished wall rack is 16 1/2 by 21 inches. Kit $8.90, from the Craft Basket (Colchester, Conn. 06415, catalogue, $1).

* For "country charm," Early American Cut and Use Stencils, $3.50 from Dover, the reprint publisher (180 Varick St., New York, N.Y. 10014).

* Easy "stained-glass" tiny train kit, $4.95. Nostalgia Station (901 W. Pratt St., Baltimore, Md. 21223). Miscellanea

* Expandable whipsnake and leather Spanish-import coin purse, 2 1/4-inch diameter, black, burgundy or gray, $10. Small Leather Goods, Neiman-Marcus (P.O. Box 2968, Dallas, Tex. 75221-9950).

* Copy-cat alligator ceramic bank for the particular preppie, $9.50. Propinquity (P.O. Box 69440, West Hollywood, Calif. 90069).

* Merino sheepskin bicycle seat cover, standard for touring saddles; narrow for traditional 10-speed, $9.50 postpaid. L. L. Bean, Inc. (Freeport, Maine 04033).

* Teacher's pet: three bars of cold-cream soap (one on a rope), with long-lasting "Super Teacher" and apple design, $5.50. The Lighter Side (Mt. Clemens, Mich. 48043; catalogue 25 cents).

* Silver-plated "bottoms-up" jigger, $10. Gump's (P.O. Box 7301, San Francisco, Calif. 94120.)

* New parents' calendar, with space for dates and notes, $7.50. Casual Living (Kent Road, Box 1078, New Milford, Conn. 06776).

* Battery-operated clip-on book light for the constant reader,$7.99. Walter Drake (Drake Building, Colorado Springs, Colo. 80940; catalogue 25 cents).

* Brass beaded rope choker, $6.95; bracelet, $4.25; Shopping International (Dept. WPN, P.O. Box 27600, Palo Verde at 33rd., Tucson, Ariz. 85726).

* Weather instrument for the amateur forecaster measures wind speed, temperature and rainfall, $7.95. Edmund Scientific (101 E. Gloucester Pike, Barrington, N.J. 08007).

* Irish linen and lace handkerchiefs, choice of shamrock or wedding bell lace, 2/$8.50. The Vermont Country Store (Weston, Vt. 05161).

* Genuine shillelagh straight from Shannon, with legend, $3.95. Shannon Mail Order (Shannon Free Airport, Ireland; catalogue $1).

* Up-to-the-minute "tuxedo" look in ladies black, pure silk tie, 3 by 46 inches, $10. Opulence (19 E. Main St., Box 1186, Uniontown, Pa. 15401). Kids' Stuff

* Stretch belt with toy truck buckle, $5. Clymer's of Buck County (Canal St., Nashua, N.H. 03061; catalogue $1).

* Count-on-Me red, white or navy knit gloves with a number on each finger for tots 2 1/2 to 6, $5. Toys To Grow On (2695 E. Dominquez St., P.O. Box 17, Long Beach, Calif. 90801; catalogue $1).

* Teddy Bear Bingo, game for prereaders, $8.50. Toys To Grow On (See above).

* Vehicle Playmat, a town to drive mini cars and trucks on and through. With traffic signals, stop signs, $9.95. Just for Kids (Winterbrook Way, Meredith, N.H. 03252).

* Snow Ski Skates to cross-country in the back yard, size-adjustable for 6 to 10 years, $6.95. Childcraft (20 Kilmer Rd., P.O. Box 500, Edison, N.J. 08818).

* Structural wood models of insects: butterfly, cricket, praying mantis, beetle. Finished models 10 5/8 to 14 inches high, $6.98 each. Miles Kimball (41 W. Eighth Ave., Oshkosh, Wis. 54906).

* Board game of Cross-Country Flying, with "realistic" in-flight situations and changing weather, $9.95. Sporty's Pilot Shop (Clement County Airport, Batavia, Ohio 45103).

* Dragon-fly kite imported from China. Hand-screened design on paper with bamboo frame and wing span of 23 x 40 inches, includes spool of nylon string, $10. New York Botanical Garden (Bronx, N.Y. 10458).

* Carl Sagan's Cosmosphere, a new design of star finder. With illustrated booklet, text by Sagan, $8.50. The Nature Company (P.O. Box 7137, Berkeley, Calif. 94707).

Note: Shop around. The price difference for the same item can be as much as $5 in different catalogues.