NAPA AutoZone O'Reilly's Keystone.com You can get them just about anywhere. They are a paint to install.
The greatest used car part search engine on the planet: http://www.car-part.com/ If you can't what you are looking for there, then it doesn't exist.
I need more details on your car, but in general I found 5 regulators in the Houston area using the above search engine http://www.car-part.com/cgi-bin/sea...502786&userUID=0&userBroker=&userPage=1&iKey=
For the record, the best online source for new parts is www.rockauto.com . Always have what you are looking for, and always at the lowest price.