As a MA resident you can buy all the non serialized PSA stuff you want, in NH. Hell you can get a NH mailing address via several means such as a PO box, ship em to yourself- how hard is that?
That only works if you also have a NH billing address on your credit card too.
I got frustrated by that many times as a Mass resident, because I had plenty of friends and relatives in NH that would accept the packages, but it was the MA billing address that the vendors didn't like.