If no one over here offers up one, try the
PCEngineFX forums.
Also, I would steer clear of Turbo Duo's and get a PC Engine Duo-R or RX, as the early models have audio issues due to the capacitors. It can be fixed, but still, just easier to get an R or RX, plus if you get a boxed unit, I believe both should have a 6 button controller with them (I know that at least the RX does).