The Best option would be to go to a Target or Best Buy on Tuesday to get the DVD. Stores typically apply a discount during a DVD's first week in release before raising the price. I get blu-rays (regularly 29.99) for 20 bucks on the day they come out. I return the next week and they settle into their regular price of 29.99.
Have you considered joining the Disney Movie Club? They have one for DVD users and one for Blu-Ray users. I joined and fulfilled my commitment of 10 movies within a couple months. If you find yourself buying a lot of new Disney releases, it's worth it. For older Disney films, Amazon and eBay have good prices as well.
If this does not interest you, the cheapest site I could find online was Overstock.com for 20.61 after tax and shipping (at that point you might as well buy it in store). I can't post the link since I'm new to this site, but just google it and you'll find it.