carrentalsavers.com was a frequent site for me when I was looking for our rental. I booked something right away that I could live with but then I would check every day, sometimes several times a day to see if the rates came down at all. For a long time they went up, making me very happy I had made a reservation when I did, but then a couple of days before the trip I caught a rental $40 less than what I had. I snatched it quickly. The next morning the rates were back up so for me it paid to keep looking often.