I'm looking for a motor can have its speed varied, down to 1 rpm if needed and that can be done with a simple circuit. I'm building a coffee roasters. I hear that AC induction motors are hard to have their speed changed. The load will be about a pound or so and the motor will spin a cage full of beans over a heat source.  I dissasembled a bread machine and the motor is induction which I have heard is not able to be accurately speed controlled. 

DC or AC? 

I've seen electric drills used to spin the bean cage. What about a treadmill motor?