This is a US based company that does what your after
http://gototelescopes.com/
Lenord currently uses the SitechServo system from Dan Gray for his goto systems.
You might want to join the SitechServo yahoo group to see mounts other people have converted to this system.
http://tech.groups.yahoo.com/group/sitechservo/
Another option if you are willing to spend more money (or find a second hand one), is the Byer Worm drive.
The only current source i am aware of is this Ebay store.
http://stores.shop.ebay.com/Telescop...__W0QQ_armrsZ1
http://cgi.ebay.com/ED-BYERS-9-compl...3%3A1|294%3A30
The other is Amart where sometimes used ones do come up time to time.
Regards
Fahim