I'd be willing to pay for one that did the switch by holding down the key (like I used to have) - but not TOO much. If I'm looking at that pic correctly (and I might not be) - it looks like an external switch is used to go back and forth.
If that's the case - even *I* (with the grabbag of crappy newb electronics skills picked up from my RC Plane hobby) could make one for about 10 bucks or so.
There's a whole howto in one of the old Grapevines (oh how I miss those diskmags).