Does anybody know where to buy (or how to make) a trackball with USB interface for less than $50 bucks? that's all that's left in my budget and I still need a trackball. I've tried google to no avail. Nowhere seems to have cheap trackballs.
I heard I can make one out of a computer trackball. do optical trackballs work? they are the cheapest ones I can find. I haven't been able to find the crayola, crystal trackball, or kidsball anywhere. The bigTrack is too expensive, and NO mechanical/analog trackballs seem to be USB.
What is the normal size of a trackball plus assembly?
Please help. i feel like I'm about to...

... yeah, that.