for pistols the "frame" is the controlled part. The receiver with the barrel is legal to sell without any paperwork.
You could offer parts on ebay with a buy it now, and get some takers before they are booted off. But if you're going to do that, you might as well sell the parts here
previously I told folks to go to ebay and get a general feel for how much parts go for. gunbroker.com and auction arms has luger parts, but many on auction arms is sold by a guy who charges too much and there are rumors that he renumbers parts (enough rumors that I am not worried about any legal ramifications
)
Ed