I think it was Model 1 Sales, at the Fall Knob Creek Shoot, they had an entire bucket full of demilled Lower Parts. I found a couple rear halves that had all of the manufacturer markings on them (Colt, GM, H&R) and figured I would grab them. That was until the guy told me they would be $100 each!
Amazing what some people will pay!
"Capt Richardson"
PS: I could see someone trying to "graft" that front half to a Colt SP1 Lower!