I have 4 gearhead motors that would make perfect drive motors for a middleweight bot. They are high torque motors from Bruno wheelchair lifts.
-3.25wide / 5" wide inc. output shaft
-aprox. 60rpm @12v
-listed as 12v but I have run another pair at 24v with no issues
- 3 of the 4 include adjustable slotted mounting brackets
$50.00 each plus shipping.