Everything old is new again. This is especially true of bamboo building materials for environmentally sound New Yorkers, who have recently embraced this self-replenishing resource as their own. Long favored in China for both structural and decorativeuses, bamboo is more durable and stable than the hardest hardwood, is ready for harvest in just seven years (instead of the 30-plus years necessary for oak or maple trees to mature), and is processed without formaldehyde or other toxic chemicals. Bamboo flooring is easy to install and comes in a luscious range of colors and finishes; see it installed at Bloomingdale'sTommy Hilfiger boutique and the Liz Claiborne flagship store on Fifth Avenue, or consult a rep at Arnson's Floor Covering [135 West 17th Street, 212-243-4993], MyHome [renovation specialists with three Manhattan locations, myhomeus.com] or Dell Bamboo Flooring [1843 Flatbush Ave, Brooklyn, 718-758-3608]. Handy types looking for style on the cheap can buy it direct from sites like iFloor.com or Build Direct.com for bargain prices.