The hands down best 45 auto on the market right now is the Taurus PT-1911 at around $580 and comes out of the box smooth as glass and with every custom option imaginable. Ambi safeties, ported and polished, Heine adjustable front and rear sights, skelaton trigger and hammer and the list goes on. Everyone who buys it is stunned by the quality and performance...including me.

But yes. You can build a .45 from scratch with parts and little hassle. I've known several who did and the results were actually fairly good guns. Problem is I don't know how much you would save and whatever it won't be near the gun a PT-1911 is out of the box where all you have to do is wipe the oil away and go the the range.