Stolen from the TARDIS Library main page:
US & Canada fans, be warned — BBC Worldwide Americas have confirmed a list of 19 classic series Doctor Who DVDs being deleted from their catalog in 2013, meaning that when current stocks are are exhausted, they will no longer be available from retailers.
So if any of these are missing from your collection, now’s the time to buy before it’s too late! The list of titles affected are: The Rescue/The Romans, The Web Planet, The Time Meddler, The Gunfighters, The Invasion, The War Games, Terror of the Autons, The Time Monster, Planet of the Spiders, Black Orchid, Time-Flight, The Awakening, Frontios, Planet of Fire, The Mark of the Rani, Battlefield, Ghost Light and The Curse of Fenric.
The Two Doctors is also on this list, however this is a special case as it appears likely to be re-released as a special edition in 2014, although without the Jimmy Savile content contained on the original.