In a lot of cases organisers work for a lot less than nothing! By not claiming any form of expences at all to keep ticket & door prices as low as possible to make sure there is a good enough crowd at an event to make the event work. Also by leaving whatever "profit" a festival makes in the festival fund to buy in the best that can be afforded the next year. Artists as well have worked for me for a lot less than they could be paid at other festivals to keep it going.
Skipy