I don't believe that simply owning parts is a crime.If anyone knows of anyone who has parts in their possession to convert a weapon to full auto, tell them what it could cost them, then walk away rapidly. Personally, I wouldn't want to know.
You can buy full auto parts online, as long as you aren't using them to manufacture a 'machine gun' you aren't breaking any laws.
There was a guy selling full auto sears at the Jonesboro gun show not that long ago, in the past couple of years.