I've buy a used engine off Ebay (or Craig's list) and rebuild it before I'd buy a short block. As mentioned in other posts you'll be lucky to find a short block from a dealer for less than a $1000. A decent block and a rebuild kit with the machine shop work might run you $300 if you take your time.
Here's a replacement block for $50.
A machine shop can turn your crank up to .020 under and you can order a rebuild kit with a rod to fit and the .030 over sized piston.