If you belong to Upromise they have a code on their site and a coupon for $15 off a 5 day rental or free day on a weekend rental. (Plus your 4% back into your upromise account)
I had that deal reserved for my dates for awhile, then Thrifty beat them by a bit, then Alamo beat them by a lot. Keep watching and hopefully you'll find a deal.
I think mousesavers also has a Walmart code you can use for Budget..we have in the past and had a decent discount. Also if you sign up on line at Budget..you get e-mail with discount BUC codes ..I think that's what they're called.