(MONEY Magazine) – ! It wasn't cool to care about money in the '60s, but that shouldn't stop enterprising ex-hippies from making some bread off the relics of their peace- and-love past. You already know how lucrative Beatles, Presley and rock-' n'- roll memorabilia have become. Now other collectibles of the period -- from Op Art plastic miniskirts ($20) to That Girl dolls ($75 to $100) -- are also increasing in value by the year. So it is none too soon to scout attics, garage sales and flea markets to uncover artifacts of the Age of Aquarius. The odder the oddment the better, it seems, and mint condition commands a premium. Psychedelic art is particularly prized, with Peter Max love posters fetching $50 and his original paintings $5,000 to $10,000. Life's 1969 cover showing a hand holding a marijuana joint sells for about $5, and furnishings of the Day- Glo era such as inflatable plastic chairs go for $50 to $100. The lava lamp (like the one at left) that you couldn't bear to pitch could be worth $75. The decade's TV series provide a wealth of opportunities. A plastic Monkeemobile model still in the box recently sold for $300. A Flintstones punch-out book is pushing $40, and a Man from U.N.C.L.E. button, circa 1965, is worth $30 to $40. Of course, the '60s weren't all fun and games, and J.F.K. memorabilia is more prized than ever. A war is not healthy for children and other living things original poster is already worth $125. To keep abreast of the market and gauge the potential bonanza in your basement, consult Hake's Americana & Collectibles Auction Catalog (P.O. Box 1444, York, Pa. 17405; $3).