I swapped THREE spare parts guns just yesterday for a nearly new very tricked out Daniel Defense V5 at a local pawn shop. They were all built with scraps and odds and ends, cheap receivers etc.....They can sell those three a lot quicker than the V5 would have and I have more AR's than I need, so it worked out good. I like building them but at some point you only need so many "truck guns" and "beater rifles"......
I have three left. Two are built on Anderson lowers- one has a Palmetto 16" M4 Nitrided upper with a Fortis rail. I let the gunsmith practice his Cerakote skills on it and it turned out pretty well....The other is a 14.5" rifle, Bushmaster barrel and Magpul furniture- CTR, handguard etc....decent little gun. The last one is probably the cheapest AR I've ever built. I bought a Smith Wesson takeoff Melonite barrel, it was brand new, guy bought two of the M&P's and wanted to convert them to .300 BO. The upper was free, part of a trade. Bolt was a $69 Palmetto blem milspec, furniture is all cast off Magpul from other projects, lower was a used Aero...don't have $300 in the whole gun.