the elitist M club don't want non-geeks having functional 122 boards.
Old M-122s are plentiful and cheap. With the right plugs, they have always worked for me with Soarer's Teensy without any drama. Plus, your re-mapping can be programmed into the Teensy itself.
If you weren't in OZ I would sell you a naked M-122 without the top case for pretty cheap. I think it has a "RJ-45" (loosely speaking) connector but making an adapter is not too hard, or it could be hard-wired.