What about Florida's panhandle? It is usually still warm, and after school starts, relatively deserted and inexpensive. Panama Beach (AKA the Redneck Riviera) has bunches of hotels all along the budgetary spectrum and, I think, a boardwalk. Destin is a more traditional resort. Seaside is more upscale. My personal favorite is Pensacola Beach.

HTH P.Miller N. Fla