You will need a decently over-speced motor to make static friction and dynamic friction negligible - there are quite a lot I've seen on eBay which are pretty decent - I've a 12V gear motor that will run down to about 0.5V (starts up between 0.7 and 1.5V from cold. Its a cheap and cheerful chinese model about 40mm diam, 60mm long (motor part), can't remember the power rating but perhaps 50W at a guess.
A smaller motor would struggle more to start against static friction, but medium sized DC motors are good value these days, I think aimed at robot traction market, mine runs well and feels v. smooth. I'd suggest its worth a try.
Something like this http://www.ebay.co.uk/itm/12V-DC-HIGH-TORQUE-High-power-Reversable-Electric-Motor-2-RPM-Gear-Box-/140860012644?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item20cbe93864
- but with gearbox removed.