A great way to save money on your Disney budget is to rent a vehicle through priceline.com. I have booked car rentals and hotel rentals through priceline many of times and have been very pleased. Last year before our Disney Cruise I used priceline to book a hotel in Port Canaveral to save not only on the parking fee at the port but to also be well rested prior to our cruise. I have used priceline the most though for car rentals.
I have found that I can save upwards of $100 on weekly car rentals. I will usually first find a rental car reservation that can be canceled and use some online discount code and book directly with the car rental company. A month prior to our trip I start bidding on priceline to try to get a price cheaper than the one I had already reserved. I also tend to check hotwire.com to see what rates are being offered and then start my bidding on priceline with about half of what was listed on hotwire.com
The only problem with priceline is that once you bid you are locked and there are no canceling. I made the mistake last time prior to our Disney Cruise by booking a Thursday instead of a Friday night and I ended up having to stay an extra night or lose out on our money. Be sure to double and triple check everything before submitting your bid.