I'm not 100% but I think that it's illegal to sell Rubber Boas. I looked into it last year and I know it's definitely illegal to sell them in Washington.

However, if you're just looking to have a Rubber Boa as a pet and are from Washington or another state that allows the live capture of Rubber Boas, then all you need is a fishing license. They don't really have anything specific to Rubber Boas last I checked...

The Washington Department of Fish and Wildlife DID email me directly on the issues, though they seemed like they were avoiding giving completely truthful answers. They stopped responding to me once I asked if I could breed and sell Rubber Boas from a state that allowed the export of native Rubber Boas.

So yeah, your best bet is to check Kingsnake once in a while or look into your state laws if you can just go out and get one yourself

(I'm too lazy to go through this right now and edit it, but Pennsylvania doesn't seem to be Rubber Boa territory, sorry)