I had trouble finding someone to swap mine out also. most shops wont do work with owner supplied parts because of the liability with the unknown quality issue. Some people will buy the cheapest part they can find then blame the mechanic and expect them to change it again for free when it doesn't work.
I found a guy with AC equipment that was a friend of a friend. Even then I had to assure him that I understood it might not work and could still be a bad compressor.
Keep asking around, you will find somebody, although you might have to wait until the weather cools and the AC people aren't as busy.