Thermal Arc Dragster 80 control knob

I broke it, anyone know where I can pick one up?

Found an owners manual online with part # 830567 (knob) listed but it doesn't look like Thermal Arc makes the dragster 80 or sells parts for them any longer.
Either that or I'm just too stoopid too find it.

These things only go for 50 bucks or so on ebay but I don't want to have to buy a whole new one just because of a broken knob...

Anyways if anyone knows of someplace that still has parts for these things I'd appreciate it. OR if you know of some generic knob that will fit that would be great too :D