Of course specialty controls in general are an odd market.
I bought a Hydra at an auction for $85, it didn't power up. It was a turd, but the yoke was nice, really nice.
It powered up once I actually hooked the AC power back up to the power supply though.
I sold the yoke, pedal, and an AKI to hook them up, and got $255 shipped for the combo.
I then TRADED the boardset for a populated Gorf panel (with the ever popular Midway top-fire style stick on it).
I used the monitor in my multi-williams and the JAMMA harness in my Golden Tee '99.
Eek, I am rambling now. What was I getting at? Oh yeah, games with specialty controllers are often worth way more parted out than they are as a whole.
I also believe that parting out a crappy Hydra conversion is something completely different than parting out a Tron.