If you go to
GoHastings.com, I think they have some of the best prices, but mabye not the best selection. Also at the websight DVDtalk they have a compare prices tool that you can type a dvd set you are looking for in and it will bring up the lowest price they find online. I havn't used it much so I don't know how many sights they use to find the best prices, but you might look into it.