With the beautiful people glistening and glittering all over the Reagan administration as well as reawakening "dressing up" throughout the nation, this fall's newest fashions are reaching for new heights in luxury. And so are the price tags of those buttery woolens, fluffy mohair knits, soft and supple silks, with their trims of leather, sequins and beads.

You though, may feel that with sales, special purchases," discount or outlet stores, many fashions in status fabrics are down to price ranges you can afford, despite what the price tags read. Are they?

What seems a bargain can be transferred into a fabulous extravagance by just a "dry clean only" label. Over a short lifetime of wear, that label can cost you two, three or even four times your purchase price in cleaning bills. In addition, some fabrics and fabric combinations might as well be marked "throw away," because once they become soiled they can be neither dry cleaned nor laundered satisfactorily.

Never has it been more important for you to read permanent care labels before you buy and then to save this information for future reference.

Never has it been of more direct value to your pocketbook to add a hefty dose of common sense to directions the manufacturers supply; to double-check your experiences and impressions with your local dry cleaner; to remind yourself of the basics, such as that light colors show soil more quickly than dark and loosely knit ones, and that woven fabrics tend to snag easily.

Warning on lame, sequins, beads and glitter: Some metallic yarns are only surface coated and will dissolve when dry cleaned. Others, made of real metal, will tarnish. Similarly, sequins and beads can dissolve in cleaning solvents or when in contact with water. Even a light pressing may cause trimming to melt, curl or discolor.

Beware of glitter that is glued rather than sewn to fabric. It cannot withstand wear or cleaning. Sparkly trims that can be removed before the item is cleaned -- bands, motifs, collars, cuffs -- are the most practical.

Here are additional fundamental guides to help you evaluate whether a luxury fabric is really an item you can afford, based on information from the Neighborhood Cleaners Association.

* Wool knits, natural fibers and blends of natural fibers, angora, cashmere, lambs wool. These should be marked "preshrunk" or your size 12 probably will be a size 6 after a single cleaning or washing. Keep in mind that the soft wool yarns are fragile, so some pilling or balling is bound to occur -- particularly at points of wear such as underarms.

When washing wool knits by hand at home, swish them through mild suds gently (never rub), use lukewarm water and dry at room temperature.

* Woven wools. Except for specially treated wools that are labeled as treated, woven wools always should be dry cleaned. (Remember those cleaning bills.) Be on guard against wool-and -eather or leather-look combinations. Imitation leather made of vinyl can never be dry cleaned if the manufacturer used careful quality control. As for the real stuff -- real suede and leather are, at best, unpredictable in dry cleaning and may bleed, shrink or stiffen.

* Mohair. The loose construction needed to retain fluffiness makes mohair susceptible to shrinking or stretching and yarn tends to separate. This is one fiber that, for your pocketbook protection, you should buy in a color or colors that won't show soil if you wear with care.

* Silk. Some silk is hand washable, but dyes used in silk bleed easily and may result in color fading. Silk fabrics are degraded by perspiration; deodorants, as well as perfume and hair spray, will affect fabric color. Manufacturers often size lightweight silk fabrics; resizing after cleaning or laundering is recommended by experts.

Caution: Silk fibers chafe, split or shred in normal wear. Tight silk jeans may look beautiful, but they're totally impractical.

* Chiffon and organza. No matter what the fiber, when fashions of these fabrics are cut on the bias (as they often are), the seams may pucker and the hemline become uneven in cleaning or laundering. Because the fabric is so light, sizing may be added to give it stability. Unremovable rings may appear when liquid is spilled on one of these fabrics.

Happy ending: You can buy most of the same luxury looks in easy-care fabrics. The labels always are on the inside, so only you need know.