Well, I just bought two of these allegedly crappy controllers from amigakit.eu. By the comments left here things aren't looking bright, but I got my hands on a cd32 console without joypads yesterday. I've searched posts and understand there are few better alternatives. The production of the competition pro has seized, and you need to empty your pocket on fleabay to get one.
Got my hopes up when I stumbled over some talk that the megadrive/genesis controller could be used, but alas... only on an Amiga :-|