Hi Jay,
Just had a look on eBay. Lots of stepper motors but not with gearboxes. I like vexta motors and there are plenty of them, some are pretty cheap. Some are 0.9 degree steps which helps. You could attach one of those gearboxes jaycar sells. Another alternative is here:
http://web.telia.com/~u41105032/Stepper/Stepper.htm
Or you can use a dc motor with a gearbox. They are very cheap.
BTW there is an excellent yahoo group devoted to equatorial platforms.
Rod