I can't see your ebay link...
But 4G63 engines are actually pretty cheap. You can get a tottally rebuilt, bored and polished engine for around 2.5-3k straight out of the crate. You can typically go to a junkyard and pull your own for 500. They're common motors mainly because DSMs come and go and their engines dont' typically last more than 90 w/out a rebuild because they're used and abused.
Howie~