I've bought a few M4s from their bonyard to fix and sell for easy money. The worst one I got was one with a broken tappet plate. The others would just have finicky external parts (like a hand guard that would not stay on) or missing receiver parts. So in my experience the guns aren't so bad. However I've never purchased a GBB from there, and the Elite Force CO2 1911 doesn't have very good spare part support from what I've heard.
That's just me, though. I wouldn't advise buying one from the bonyard.
That's just me, though. I wouldn't advise buying one from the bonyard.