Brushless motors are more common in high-end drills - most brands have one or two models in their range. The motors have WAY more torque than their equivalent brushed versions; both of mine will shear off screw heads and damage your wrist before they stall. I had a look at replacement motors on a spare parts site and the main issue was that the motors had casings that integrated with the drill body and gearbox, so using it outside of the drill would be complicated. Other brands might be different, but the ones I saw are nothing like a convenient 550 or DeWalt brushed motor. If you can get the motors for free its worth experimenting, but work on a plan B as well.