i dont know about the cape, i think you can buy day passes. I bought an annual pass to a particular beach for $275 (ouch!)
usually, i don't think you need to be a local resident to any extent. if you don't live in the town the beach is located, though, you tend to have to pay the higher option. the locals only have to pay like $40 for the one I paid $275 for, as an example.