I've ordered countless DVDs from
www.deepdiscountdvd.com using the free shipping option and have never had a problem with an order. No order had ever taken longer than two weeks to arrive - except for ordering pre-releases, but that doesn't really count.
You should try
www.dvdpricesearch.com to find the lowest online price. 80% of the time it will probably be deepdiscountdvd.com. You might also consider joining the Columbia House DVD Club following the guidelines from the Clubs forum over at
www.dvdtalk.com. There's a great deal of info there on how to get the most for your money.
Hope this helps and good luck,
Ken