A good place to educate yourself and look for deals is mousesavers.com. I just got a van for my Jan trip for 247 including taxes with
budget. Using codes that I found on Mousesavers.com currently in there hot deals section.
The trick with car rentals don't rent from places like orbitz or travellocity. Use the Car rental company website, and don't be picky about the make you are only using it for limited period of time. Do not and I repeat do not prepay. Also when you are looking find the best deal you can and take it doesn't matter how much. At least you know how much you have to pay. Then once a week at least look at the prices and new codes coming out if you find a better price book it then cancel your old rental. Two weeks before your trip I would start checking at least 2 times a week sometimes you can get a last minute deal. When I went to California this summer I ended up getting a car 100 less than the best deal I had from the same company, and I did this the day before I left.
Watch out for the customer counter they try to sneak little additions just pay attention to what they are saying. I really strongly advise going to mousesavers.com and looking at their car rental section great advice about just general rental stuff people need to know about.
Hope this helps
Paul