A few years ago I needed an extra lower because I had one upper too many.
Guy at a gun show was selling lowers (among other things). He had complete uppers or would sell you the parts to build your own for a little less.
I desided to buy the parts and put it together my self (excluding triggers, there isn't much difference between lowers, even if you want a target rifle).
Turns out he didn't have enough parts and starts taking a complete upper apart.
I tell him that's silly, he's wasting my time and his in disassembling the gun. Saying he could just sell me the upper for the price of the parts since he didn't have the parts, plus besides being able to make a sale, he wouldn't have to waste time in disassembling the thing.
He thought a minute, laugh and handed me the upper.
I put on my White Oak, put in a Geissele 2 stage match trigger (trigger cost more then the lower). It shoots as good as the WOA did on the Colt lower. Plus I was able to put my SP1 back together.
Put the money into the upper. Excluding the trigger, that's where the accuracy is.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071