Rumor has it there is a good aircraft paint shop at the RYV airport halfway between msn and mke. You can probably find a phone number for the place in a handy AOPA guide. When I drove out there on Saturday they were stripping a T-6 and several other planes were awaiting work...like usual. My buddies dad had his Bonanza painted out there, no complaints. There's always planes out there getting painted, so the reputation must be good.
Also, on the east coast, there was a pretty good shop just north of Charleston SC. But I don't remember the name of the place. A google search should net a location for that place.
There's a place at Ozark, AR (7M5) that we had a Navajo and a Sundowner painted at. They do a 'wet look' finish that makes the paint look like it's covered in water---very nice looking. I don't remember what he charged, though.
Remember, you get what you pay for - especially when it comes to paint jobs. I've been doing some checking lately and good jobs will run $7,000 to $11,000 for singles and about $5,000 more for light twins. (That's nothing though, if you want to feel what a wallet cramp feels like, get a quote from Duncan Aviation to paint a Falcon 50. )
The big thing is to get a list of references and talk to them.