as a promoter, if you agree a fee whatever it is you pay that fee, end of, even if three people attend.
Too many times I've driv 80 miles to a function, done me bit, had a beer and a dance gone looking for said bloke to obtain said fee which just about covers travel expences only to be offered a soul brother shake and a "sorry mate numbers down pay you next time"
I'm all for keeping the faith and all that bollocks but twat I am not.