The highest prices I've seen offered were somewhere along $200 to watch an M/F show.
But you should consider that these days, everyone has access to the internet. Which kind of make voyeur shows almost obsolete.
A few things to consider:
1) People have the internet; they can be voyeurs in the comfort of their own homes.
2) The stamina of either the male or the female
3) The location, somewhere that would accommodate the "voyeurs".
4) Serving popcorn & maybe sodas to recoop any costs