Looking for sources of low cost NEMA size 17 bipoloar stepper motors

Hello,

We are looking for sources where one can purchase NEMA size 17 stepper
motors. The motors should be bipolar, however we are open to the
possibility of using unipolar motors. We are looking to spend $25-50
max per motor.  We are also looking for motors that are high torque,
in the order of 100 oz-in miminum holding torque, but closer to 150oz-
in would be better.

Can someone point me to a manufacturer, distributor or surplus outlet
for these?

Thanks
Mike McWhinney