I've got some Ultimate FB Interface boards in stock if anyone is interested. The cost is $60 shipped.
This is an almost a drop-in controller board solution for Intellivision, ColecoVision, and Atari 3-7 Flashbacks and use the FB's existing PCB mounts and screws. This board then hooks up to your Raspberry Pi via a 6" USB cable. If you're putting it in an INTV FB, you'll need to remove the tiny horizontal tab behind the player1 port. If you're installing it in a CV FB, trim the tab behind the player1 port for the board to fit. Since the board is upside down in an Atari FB, player1 and player2 ports will be reversed.