baseline, you're going to pay upwards of $3k for a built shortblock. installation should be around $1000 - $1500 to pull the motor and completely re-assemble it but every shop is different. then, while the engine's apart, what else are you going to want to do to it? if you're taking the heads off anyway, you might as well get them ported. if you're taking apart your heads, you might as well put in cams. with all this being done, you're going to need headers and a better clutch. the whole thing can turn into a $10k project real quick.
the benefit of using a built shortblock from mph or vt or dss or chp over just putting in your own forged parts is that those guys hand build blocks all day, every day. they know exactly how to put it together and balance it to get it right. if you're an expert, you might save some money doing it yourself. personally, i'll leave surgery for the surgeons.