Here are a few I know of:
http://www.sciplus.com/s/c_15/5
They have a “MAXON Swiss made gear motor”
An old place:
http://www.surpluscenter.com/electric-m … earmotors/
http://www.surplussales.com/motors/Motors-1.html
Found another Maxon motor:
http://www.skycraftsurplus.com/3vdcmoto … ction.aspx
http://www.electronicsurplus.com/leftnav/motors/dc.cat
Has some ESCAP Motors but didn’t see any with gears
I’ve bought from this place a few times. Has Maxon &Faulhaber gear motors:
http://www.allelectronics.com/make-a-st … ors/1.html
http://www.bmius.com/c-235-small-electric-motors.aspx
This place is mainly Optics but can have small motors. They are about an hour from me so I have been there a few times and its great fun looking at everything.
Also, Google “surplus DC gear motor” to find lots more. It does take some time to look to see what is available. Then more time to try and find specs. Some time spec can be found (for off the shelve parts) but many times surplus items were originally custom so no specs.
I have not bought from most of the places I listed above. With surplus I tend to buy what I need from where ever I can find it so not a repeat customer.