I can only recommend to look for old, unused scanners and to cannibalize them!
They are a great source for all kind of goodies. For example, the UMAX SCSI scanner I dismantled today provided not only a nice stepper motor:
… but also a precision rod (with bearings), timing pulleys, a timing belt…
… a 12V fluorescent lamp, great for illuminating a MakerBot…
… and lots of other useful stuff like a bunch of cables, mirrors, a sheet of glass (I plan to use this for equipping my MakerBot with closed windows…) and last but not least a spring which was used as a kind of drag chain in the scanner:
I try to use it in the very same way for the X/Y stage cables in my MakerBot (as soon as I figured out how to insert the cables into it without cutting off the connectors).
Since I intend to use the stepper motor to drive an experimental extruder, I’m working on, I did a test drive with a MakerBot extruder controller v2.2:
Again: It’s absolutely worth it, to cannibalize an old scanner. They are easy to dismantle and the yield of useful parts is amazing!