I don't usaly work as a freelancer on a hired basis, but since i'm doing alot of work like that now, i charge a flat fee of $599.99. And then where im selling my services i higher or lower my price. For example at TalkFreelance (no disrespect) i know there isnt much of the green stuff flying about, so i lower my price. 1 day i might get a job from TF for 400$ the next day i could get a job for 300$..