A "milspec" or basic gun is not the same as a cheap knockoff. The Springfield MilSpecs and GI guns are good. The few Colt 1991s I've seen, while not "milspec," have been decent guns. Inexpensive military surplus 1911s are a thing of the past, but if you get really lucky and find one, it'll certainly do.
No, I'm talking about "off brands," like the pimped-out, made-in-the-Philippines $380 RIA the original poster mentioned -- not basic guns from good makers.
I'd have to run some numbers, but I'm not sure buying a basic gun and then having it 'smithed (at least by a good gunsmith) is cost-effective compared to buying a 1911 that's ready to go out of the box.