Like mentioned http://ultravioletcinema.com
They will give you a list with prices from a slew of websites that offer codes. You will find most have similar prices however on occasion you'll find a deal.
Its a great site and I figured how to use and search for it, but why is it that almost all of the sites have the same movies and all of them the ones released in the last few months to a year.
Do any of you use discounted iTunes gift card and buy movies from iTunes when they go on sale to add to your collection?