The clothes here aren't just old, they're insane. Wonderfully, utterly insane. Amiable proprietor Louis Merisola is quick to tell you why: His wife, Linda, is a show-biz wardrobe stylist who outfits actors for films and TV commercials. Which explains why you're likely to find more than one hot-pink marabou peignoir on display at this hip downtown boutique. In addition to new-issue, retro-look togs, Spine offers some incredible vintage items, like garish dinner jackets, shocking layered-chiffon capes, and the swankest period sleepwear and smoking jackets you'll find in town. Prices vary, but the time saved seeking a vulgar solid-gold-sequined trench coat or a Busby Berkeleyesque lamé-lapeled tuxedo is worth a couple of extra dimes.