Clunking noise

My minivan is making a clunking sound at the rear. I've had unqualified people tell me that it's likely my axle or that the tire is loose. When I turn the wheel I hear strange clunking sounds at the rear of the vehicle and sometimes FEEL the clunk in the floor. I'm curious to know what is involved in repairing the problem, both cost and labour time. What could be the source? Any help would be greatly appreciated! Thank you so much.

My wife liked to drive the passenger rear tire off of curbs. I finally discovered that the clunking noise was coming from a bend lower shock -absorber mounting bolt. Only available from the dealer about$8