I dunno if you missed my post recommending Falcon...but their prices are the best you'll find. When I called around the local auto parts stores (NAPA, Autozone, etc) the pistons were ~ $45 each. I got the same piston (Speed Pro) for ~ $16 from Falcon. And for whats its worth, I'd REALLY recommend replacing all of them while you're in there. You'd hate to have this happen again.
2000 WJ 4.5L - Stroked, Locked, & Long-Armed
Looking for 6" WJ springs!