At work I've used a few small brushless dc motors (10 oz-in) from Pittman (who now seems to be part of Ametek) and I was happy with the performance and very happy with the technical support when we were deciding on specs and choosing the motor. They make much bigger ones too:
Also, we just bought a brushless dc motor to test from Anaheim Automation, this one is 135 oz-in and again, they have much bigger ones:
For us, low cogging isn't that important since we run fairly constant speed usually between 2 and 4000 rpm, but getting the driver electronics onboard was nice for our packaging, and, of course, cheap is vital :-). I got a price from Moog and the motor may have been great quality but the price was over triple Anaheim's price.
Where do you look when you look for motors?
I'm looking for brushless motors in the 200-250oz-in (1.5-2Nm) range; something with fairly low friction and quite low cogging torque is preferred.
It's been a while since I've selected motors, and to date everything I've done is more in the Maxon sort of size range, so I'm not sure of the best places to look.