we're in the latter stages of doing a bulk order of stepper motors. (you might wanna skip to the last page of that for up to date info)
currently, we've narrowed it down to 2 motors. i've ordered 1 of each. 1 has arrived and the other should arrive shortly.
i plan on testing them tonight (or at least one of them) and i'll post my results in that thread when i find out which one works best. i have a feeling the dual shaft one is going to be the motor of choice.
of course if you're itching to get started, the links to order them are located in that thread.