What's the deal with the different costs of Blu-Ray movies?

[BigPaesano]

I recently found this site to explore all of the current and future release Blu-Ray movies. I noticed that the prices for the movies I'm interested are VASTLY lower than those of the stores I frequent to purchase these movies (e.g. Best Buy, Circuit City).

Are there ANY differences in movie/feature quality if I purchase my movies from Blu-ray.com versus the other stores? I'm looking at these prices like "if they're too good to be true then they're not!"

Also, what are the best places/sites to purchase these movies without compromising customer service?

Thanks for the help!

================================================== ========

46" Samsung 1080i w/ DIRECTV HD, PS3 w/ 3 games and 8 movies