This fantastic c.1965 handbill advertising Merry Prankster Ken Kesey's Acid Tests, and signed by Kesey himself, is up for bid right now in "The HeART of Rock and Roll Poster Auction." It's already up to $6,300! Collectors Weekly has more on the handbill and an even rarer Acid Test flier also on the block. "Rare Acid Test Posters Flying High"