Before anybody starts calling the performers on the weekend greedy, let's consider what factors were at work here. Some of the biggest bands in the world were being asked to play at a festival nobody had ever heard of, organized by people with no reputation, at a location that changed three times during the planning stages. The acts were understandably a bit wary of the setup and demanded fees that would make it worth their while to attend.
Jimi Hendrix was paid $18,000 (and put on at 9am on Monday morning - we're not over that), Jefferson Airplane took double their usual fee at $12,000, and The Who, Janis Joplin and the Grateful Dead insisted on being paid up front in cash before they'd agree to appear. Nobody sensible would have gone ahead with this festival.