I started with a complete LQ4 that I pulled from a 2005 GMC 2500 work truck. I tore it all the way down for inspection and dropped the block and crank off at a local engine builder. No excessive wear was found, so they polished the crank, honed the cylinders and sent me home with main bearings, cam bearings, Speed-pro flat top pistons and a piston ring set. I scored a nice set of 243 heads to replace the 317 truck heads. I ordered a Brian Tooley Racing Stage 2 truck cam along with a new set of springs that I probably didn't need. I decided that since I now essentially have an iron block LS2, I should think about fuel. I bought a set of LS2 injectors on eBay and built some .200" spacers so they'd work with my truck intake and fuel rail. Lastly, I scored a free pair of LS3 exhaust manifolds from a 2010 Camaro. I believe it should be a relatively strong and reliable power plant for my new buggy... time will tell.
complete LQ4 - $1000
243 heads - $300
BTR cam & springs - $460
LS2 fuel injectors - $100
oil pan ~ $200
machine work, piston, rings, bearings ~ $900
engine gaskets, oil pump, timing chain set ~ $1000
Total... <$5000