If you are trying to determine the sex of your bunny, check out this site. They have a pretty good way to do it yourself. If you're asking the cost to desex a bunny, call a vet.
http://www.wikihow.com/Determine-the-Gender-of-a-Rabbit
Do vets charge a lot to sex a bunny?
im sure it doesn't cost much to sex a bunny.. Not sure how the bunny would feel about that.