Stuck record here:
1/ Don't use a stepper motor. Too much noise, too much torsional vibration, and it needs a special controller.
2/ Use a brushed DC motor with a gearbox and a straightforward PWM speed controller.
The gearbox is essential - it allows the motor to run at a speed where cogging is irrelevant. Something like the innards of a cheap cordless screwdriver might be ideal. Possibly a bit slow. If so, check out Benta's recommendation for a cheap geared motor. If you've got a variable voltage bench PSU, you can run that motor off that. It's what I do.