How much does it cost to get a bathroom rough plumbed?

I had a friend rough plumb our basement and I am wondering how much we should pay him for his service, other than parts?

If you brought in a plumbing contractor - you would've probably paid around $250 per fixture for the rough-in. Seeing how it's a friend who will probably say that he/she wants nothing - give them a gift that reflects your appreciation. Dinner & a show, fine wine or liquers, ski pass, spa pass - something that will let him/her remember you by. That's what I'd like
He hasn't given you a bill? No mention of prices before doing the work? Is he a plumber by trade? If not, how confident are you he did the work correctly? Impossible to quote a price for the work without knowing a ton of details about the work done.