Help me understand rebuild vs crate?

I am in Elbert Co, which is South East of Denver.

I look on CL here for Magnum and LA motors and there is rarely anything. I have been down to the Springs several times to look and everything was junk. right now there is a 5.2 magnum that needs a complete rebuild for 400! No thanks. I am doing a 390.

You're looking in the wrong places then. Forget Co. Springs, if you're up to the physical challenge, hit up the Pull-and-Pay yard over in NW Denver near I-76 and I-70 junction and grab a Magnum yourself. I got a full 5.9L shortblock (with cam and lifters) for $125 from my local self-serve yard in Greeley out of a 2001 Ram 1500 and it needs NO machine work... cylinder bores still have factory cross-hatching and bearings look almost brand new, and the truck it came out of even was beat completely to hell. Just a suggestion, since I've been down the "I want to rebuild it myself" road as well and from experience you can save quite a bit of money if you're smart about gathering good used parts instead of using brand-new everything, especially for just a driver vehicle... JMHO