Shop, shop and shop some more!
Just last week I wanted a rental car to drive from Orlando to Tallahassee for an overnight trip to FSU.
Just kept shopping the best price for a full-sized car, tried all the normal travel sites and couldn't find anything under $40/day. Then I got an e-mail from Travelzoo.com and was able to get an Alamo price, lower than the Alamo site was offering.
I know many horror stories have been said about Alamo, but I had no problems. Pick up was at 9pm, no line. The agent did try twice to get me to upgrade my car, and once with the insurance, to no avail.
You really should get a good rate due to the length of your stay.