Where can i find the cheapest rental car?

I would like to find the cheapest rental car possible. I need one with unlimited mileage that is in Tucson az. I will be traveling from Tucson AZ to Anaheim ca (Disneyland) this weekend. I am fine with just a small 2 door compact car.Where can i find the cheapest rental car?
I am assuming a weekly rental for a car picked up at the Tucson International Airport (TUS) and driven to Disneyland and back to the airport. I checked on Expedia and economy rentals starting at $220 at Thrifty and going up for bigger cars 鈥?Hotwire has an economy car starting at $180. With Hotwire, you do not know the agency that does the rental until you book it 鈥?I have used them a bunch of times with no problems. Your rates may vary based on pick up and drop off dates. Many agencies have coupons for discounts on weekly rentals, so you might want to do a search for those as well. Good luck and safe travels!