My 3-Gun AR started off with a 100% Del-Ton complete upper. Super cheap, and I mean suuuuuupeeerrr cheap. It has about 3000 rounds on it, maybe more, with zero issues. The upper receiver is still on there, as well as the charging handle, forward assist and dust cover assembly. Oh, and the Del-Ton BCG is still in there.
The carbine I put together in the fall was 100% cheapest parts available. AO Precision upper (which I bought after UPS lost my PSA upper) and BCG. Del-Ton barrel from the upgrade of my 3-Gun AR. Model 1 free-float tube ($35 with barrel nut!!!!!). Heck, the Aimpoint I put on it is worth slightly less than the gun itself. It only has about 200 rounds down the pipe, so it's still brand new, but it shoots like a laser, and is fault-free so far. I might send it to Accurate Iron to have the roll marks filled in with robin's-egg-blue watercolor paint. But I won't pay more than $3.50. This gun is cheap!