I currently have two Pumkinseed and I love them. They are very unique in both look and personality. Smart fish, very much a "wet pet" kind of native! I caught mine locally, but a lot of states wont allow that. There are site and places to buy them online.
Somehow the state has never been magically aware of what I've had in my fish tank, so I personally have never worried about it. You'll have to make your own call on that one. I've kept various "native" freshwater fish. Keeping these guys, or any other sunfish or bass is analogous to keeping cichlids, and they are basically the North American ecological analogs to these fish.