The receiver is easy to buy; you just use your own credit card. The hard part is finding a local FFL that will receive and transfer the receiver to you.
Before you order the receiver, call around to your local gun shops (FFL holder) and see who will do the transfer, usually for $20. Once you find one, they will need to send a signed copy of the FFL to whom every you are buying the receiver from, then you can order the receiver to be sent to them. Once they have it in hand, then all you need to do is go down, fill out the Yellow form, pay the $20 and it’s yours.