They do good work.
It looks like that price includes all the drive system, electronics and fuel stuff, so that explains some of the cost.
Anyways, they sell a TON of engines and thier assembly proceedures seem very organized (when I was there).
A stock LS2 is around $5,500 from GM. Now add up all the stuff they do to the engine, all the included "stuff" and you will see if it's a deal or not.
Simple.