We've stayed at the Boatslip on Commercial Street. More a formula motel, not a B&B, we spent so little time in our room we really didn't care. Plus it has weekend gay tea dances, is on the beach, with a swimming pool, its own bar, and free on-site parking, some of it covered. We got a near $300 room for under $100 in the off-season in 2010.
Most of the lovely Victorian-style guesthouses have no on-site parking and no beach access. They tell you to go down a few blocks to a public pay parking lot, which you have to figure into your cost & convenience. Plus they may have steep staircases and no elevators, a factor for us but perhaps not for you. Still, some are quiet charming, and all gay, which the Boatslip is not, despite the tea dances it holds, that are open to the public for a charge anyway.