You could use the MFAComo Drills 940D 100:1 gear motor, max torque 416 oz-in and as inexpensive as $32.31 USD (for 10 or more) at Technobotsonline in the UK:
The downside is if you choose Fedex (1-2 day shipping) like I did, they assess all sorts of stuff so I ended up paying about $150 for shipping/customs/brokerage fee and taxes. Best to choose airmail so customs clearance is done by the post office and you will save a fair bit.