It surprises me that the vets you called don't do it. It is pretty standard practice now days. Plus it is a big profit maker as the chips cost about $5 each and most vets charge between $30 and $50.

I would try calling rescue organizations in your area. Most rescues use microchipping as a fundraiser and generally have microchip clinics pretty frequently. You can also try calling the shelter in your area to see if they know anyone who does it.

Petsmart use Banfield microchips which run off a different frequency than the Avid and Home Again chips. Most shelters and vets do not carry the Banfield readers (although check with your shelter to make sure) and the Banfield chips cannot be read by the standard Avid readers.