I'd go south
We had opposite experience. We looked hard for a low-mileage, Limited Gen 4 4R in great condition and finally purchased one from a Minnesota dealer. But we're used to Colorado cars and were too trusting. We had a _long_ and I thought comprehensive and detailed conversation with the dealer before my wife flew up to get the car. It was a single-owner car, interior perfect, less than 70k, etc. I very specifically asked about rust, which was a big concern.
As soon as my wife saw the car she called and sent pictures. Lots of rust underneath, in the engine compartment many of the bolts/brackets are rusted, and there was a sort of dusty, corrosion coat on the aluminum rocker arm covers. Even when I had pictures in hand and had the dealer on the phone, he's trying to tell me it has "... basically no rust - nothing to be worried about". That's BS.
In the end we purchased the car anyway - it was in great condition other than the rust, which is mostly the frame and stuff under the car (especially towards the rear, including brakes, brackets, fittings, etc - anything that's a ferrous metal), and in the engine compartment. The body is excellent. Mechanically I don't think we could do better. I love driving the car and I expect it'll be good for MANY more miles, but I'm dreading the day I need to work on the suspension or other system where all those bolts are rusted. And I just don't like having a car with rust.
Bottom line: I doubt I'll ever get another used vehicle from a rust-belt state. I'll look for one from the SW, and I'm willing to travel to get it.
