I'm in Illinois. I see them on Craigslist all the time. I know they are prohibited but people still list them. Look in sporting goods. They usually survive until someone reports them and the ad gets taken down. If the right person sees the ad in the hours it is up, the gun will get sold.
Apparently selling gun parts on Craigslist is ok. I saw a Ruger .40 recently that made it several days. The seller was selling the parts for the pistol but since they were pretty attached to each other they would have to be bought in one lot. He included 4 pictures with a different part of the gun in each picture. The whole thing added up to $400.