For sale, one used Cordless Optical Trackman from Logitech like this one:
http://www.logitech.com/index.cfm/products/details/CA/EN,CRID=2150,CONTENTID=5006

Works fine.
few cosmetic marks near the rear (slight faded of the logitech logo from hand resting on it)
comes with: the unit itself, plus the receiver
no software included, but easily downloaded at:  http://www.logitech.com/index.cfm/downloads/software/CA/EN,crid=1780,contentid=5291,osid=9

Asking $50 considering brand new ones are $100.

Cheers,
Keebmeister

ok...so maybe $35?