According to this unsourced bit making the rounds on Facebook (probably posted by Abraham Lincoln using the lobby wifi at the Ford Theatre), Jimi Hendrix got paid $18K for his appearance at Woodstock ($116,129.03 in 2014 dollars, according to). That seems completely reasonable. It was an iconic, generation-anchoring performance.
On the other hand, I feel sort of bad that Sha-Na-Na only got $700 ($4,516.13 in 2014) for this:
(And in case you have some anthropological curiosity about what a "hop" was. . . . )