(FORTUNE Magazine) – Will a poster of Jimi Hendrix ever hang side by side with a Monet? Probably not. But it may prove a better investment. While prices for impressionist paintings, classic cars, and other hot sellers of the 1980s are collapsing, rock & roll posters are the thing to watch. They are still comparatively cheap, but prices are rising quickly. The most sought-after feature big names from the 1960s, like Hendrix, Janis Joplin, the Grateful Dead, and the Doors. Says New York City gallery owner Jay Kastor: ''Ten years ago only poor hippies were trading these posters.'' Times, they have a-changed: Kastor, who in March paid $1,000 for the Hendrix poster shown here, wants $4,000 for it. Such prices bewilder Robert Salomon, a managing director of Salomon Brothers who claims never to have even heard of Jimi Hendrix. Says he: ''Collectibles aren't an investment; they're a means of conspicuous consumption.'' He suggests that investors go for high-grade bonds and Treasury bills instead.