I found Epson Stylus 580 on the road the other day (someone throw it away) and it had timing belt on the printer head, ~30cm in diameter - I think ideal for the purpose. The timing pulley was on the stepper motor shaft.
The tricky part was to remove the glue that was holding the belt in place on printer head and not to damage the belt itself.
I think majority of today's printers and scanners will also have them, as this is proven, accurate and cheap solution for linear moving parts (print heads, scan heads etc).
You can also purchase those things at Small Parts (
http://www.smallparts.com.au/hobby/.. a bit hard to navigate this website..) or here:
http://www.sdp-si.com/Press/New/Belts2_5.htm