How about if I ‘find’ a gun, and offer to return it to its original owner, of course gratefully accept a $599.95 (or, whatever) ‘reward’ for my efforts?
Under the Toomey bill, you committed a Federal Felony for failing to obtain a background check before picking up the "found" gun, and you and the "rightful owner" both committed another felony for failing to obtain a background check before transferring the firearm from yourself to the "owner."
The $599.95 "reward" could be zero and you'd still have committed a felony.