If you are a fan of photography in documentaries, the new Cosmos with Neil de Grassy Tyson, "A Spacetime Odyssey" made its debut this Sunday on TV and the DVDs and BluRays of the first season are now available for pre-order at Amazon.com. The BluRay set goes for $42 while the DVD set goes for $35.
Amazon.com offers a pre-order price guarantee on media pre-orders (books, movies, video, software, video games), so you will pay the lowest price between the time you pre-order it and the end of day of the actual day it ships. If the price drops below your pre-order price, the price of your pre-order will be automatically adjusted in your Orders page (usually a few hours later). If the price drops on shipping date, your payment will be adjusted accordingly (depending on credit card or gift card and such). You don't need to contact customer support for the price adjustment, their computers take care of it.