I got my servo motors from:
They usualy have some that are pretty hefty. The ones I used on my mill/drill are 48V 1000 rpm units about 11lbs each! Prices aren't to bad, but they do NOT have encoders on them. I put my encoders on the lead screws so I could play around with the pulley ratios and not effect the settings in my TCNC program.
Of course, YMMV, and usual disclaimer.