M.C.
I agree with the suggestion to try hotwire. You don't get to choose the company--in fact, you won't even know the company in advance--but I've gotten rates as low as $16/day through them for a full-sized car. You WILL rent through a major company (you can see the list of who they use on their website), you just won't know who until you've paid. You also have to pay in advance, and it's non-refundable, but for a great deal, it can be worth it! GL!