Highlander - Have you tried BookIt.com - they seem to have very low prices.
My suggestion would be to book just the first 2 days via internet then do walk-ins and negotiations at places you find you like.
If you did it the first day, going to places with bags in hand/taxi, it would make you look desperate for a place - plus you'll be hot and tired.
The second day you can devote to it while checking out the beach - then just move at check-out time the following day.
Ask to talk to the manager (or owner). Lots of time the rsrvtn/desk person doesn't have the authority to negotiate.
I have done it many times - even at Christmas. The only time I would say NOT to try it is for ATL.
