Please consider Gear (reduction ) motor p12 6V 60RPM as an alternative.
Pretty nice Gear Motor with dust-proof enclosure, running at 6v 60rpm.
Operating Voltage: DC 2.4 ~ 6.0V
No Load Speed: 55 ~ 70rmp
No Load Current: 30 ~ 70mA
Max. Efficiency Speed: 40 ~ 52rpm
Max. Efficiency Current: 350 ~ 450mA
Torque: 0.7 ~ 1.2kg.cm
Stall Current: 500 ~ 700mA
Stall Torque: 3.0 ~ 4.0kg.cm