Checked on McMaster... the prices range from $135 (team numbers in everyday places
) to $972
.
One major major advantage to these motors is that in a low torque application requiring super high rpm such as engraving or micro-machining, these things rock... the cheapest air motor has a top speed of 10,000 rpm at 90psi, 18cfm... we used these at the place I work to do some engraving 1/32" ceramic end mills.
Well... I have a question about your robot too... how fast did it go? did you have variable speed? was it reversable? if you had variable speed, how'd you do it?
-q