My husband and I go to IOP a lot in the summer months. Anything you find in the 20s 30s or 40s is decent. Most houses that you can find on the east side of the island would probably be a short walk to the beach. The residential area is nice, and most houses have driveways. Beach access is normally available once a block or so.
When you go, just make sure that if you need to go to the grocery store, go before you get on the island, the one grocery store on the island is pretty limited. (theres are target and a piggly wiggly right before you to the island in Mt. Pleasant