Okay cool, sold as is sounds good, so yeah a grading system for quality would be a plus. Windy City has builders parts kits for $995 everything included except receiver, bolt, and barrel now that's 995 US. And seeing as these are everything included except receiver and full auto fun bits, in all reality I can see them starting at lowest maybe $1050 and up to $1400 depending on what you paid for em to get shipped here. I don't imagine any of these parts will be so abused that they will be unusable so for a low grade start at maybe $1050ish and for medium $1050-$1150 and for high $1150-$1400. Will you be doing the chopping up of the receiver's yourself? if so anyway we might be able to get the heels you know for a fancy paerweight?
In reality folks these parts are not being made and are getting rarer and going up in value I would not expect them to come cheap.