Steve...you can go on the ASCAP website and request a rate sheet. You can generally negotiate down from the rates. the New York office will put you in contact with reps for your state. You counld do that, and tell the owner what you find out. The owner can also contact other club/restaurant owners in the area, who can generally help with making the right contacts.
If the venue already has music but isn't paying fees, I'd be careful. You could inadvertantly trigger a request for back fees/fines.
Good luck!
R.