I'm building a tipping semi trailer, so needing loads of torque in my screw drive motor.....I found this website with an incredible range of gearmotors - dimensions, voltages, currents, gear reductions etc. Look under 'motors' - each motor type gives numerous gear reduction options.
http://www.technobotsonline.com/
I'm using something similar to a 540 motor with 100:1 reduction which I figure will shift almost anything. I figured to pick the largest diameter motor possible for the available space, then pick an appropriate gear reduction to get the right RPM....
For control, I'm using 'H-bridge' relay set up which is a) cheaper than ESC and b) provides direct battery voltage to the motor so improved power transfer.