Years ago when I scheduled my first research trip to Collector's Eye, I allowed about an hour to check out the wares. Af ter three hours, I had to tear myself away, only to return again and again to revel in the nostalgia of the costume jewelry of days gone by. Designers like Eisenberg, Hobe, Miriam Haskell and De Mario might not set some hearts fluttering, but to those who are into vintage jewelry design, there's glitter on those names, and owner Merrily Flanagan knows it.Flanagan, who has been collecting antique jewelry for more than 20 years, has a network of providers from Florida to New England and Montana to the Mexican border who consistently supplement their incomes by sending boxes of old costume jewelry pieces they have gleaned from various sources to her Canoga Park store. On arrival, an item may be kept intact, it may be dismantled and used to design another piece or the parts may be used to repair an existing design.So extensive is the selection at Collector's Eye that European dealers send their shopping lists for fulfillment, she says.Flanagan goes to the East Coast on buying excursions two or three times a year, but she's just as likely to uncover treasures right here in L.A. She speaks with pride of the 1930s Joseff of Hollywood amethyst clip she recently turned up at a Santa Monica boutique. Joseff was a noted designer for the studios in the early days of Hollywood, when costume jewelry began its climb. Whereas you might expect to pay $150 or more for this, the price at Collector's Eye is $47.50. Advertisement This beautifully organized shop is set up so that each color or stone has its own area. Pearls are all on one table, rhinestones on another; a table for jet or onyx may be adjacent to a table devoted to amber and topaz pieces. Another area is just for cameos dating from 1850-1950, most of them under $40. There's a wonderful box of sterling charms--all marked $7.50.Currently fashionable are Victorian and Deco watch fobs that are worn as necklaces, swags or on a belt. Collector's Eye has an enviable inventory of sterling or gold-filled fobs ranging from $35 to $95.The best way to shop at this treasure of a store was worked out by the owner. Take one of the many velvet trays and wander from one display to another (there are 45 altogether for about 10,000 pieces), placing whatever you like on your tray. Be good to yourself and allow plenty of time; I predict you will lose track. The record for browsing is seven hours, set several years ago by two women who forgot about time one day at Collector's Eye.Where to Shop Advertisement Store: Collector's Eye.Location: 21435 Sherman Way, Canoga Park.Hours: 10 a.m.-6 p.m. Monday-Saturday.Credit cards: MasterCard, Visa, American Express.Call: (818) 347-9343.