Cheapest I've seen this utter classic Dr Who DVD. Cracking story and way better than the remake.
The Tardis materialises in London sometime after the year 2164. Dalek invaders are now ruling the Earth with the aid of humans converted into zombie-like Robomen, but they are opposed by a group of resistance fighters led by the wheelchair-using Dortmun. The travellers discover that the Daleks have established a huge mine in Bedfordshire, their aim being to remove the Earths core using a huge bomb and replace it with a powerful drive system so that they can pilot the planet around the galaxy. Ian manages to create a barrier in the shaft in order to intercept the bomb. The resulting explosion destroys the Daleks and their mine and creates a huge volcanic eruption. Susan has fallen in love with resistance fighter David Campbell, and the Doctor decides to leave her on Earth to find a new life with him, while he continues on his travels with Ian and Barbara.
On The DVD: Doctor Who--Dalek Invasion of Earth is a comprehensive two-disc set with a generally excellent black-and-white 4:3 picture and mono sound. The highlight of Disc One is a warm and very informative commentary hosted by Gary Russell and featuring director Richard Martin (all episodes), producer Verity Lambert (5 episodes), Carol Ann Ford and William Russell (4 episodes each). There are optional subtitles for the episodes, as well as for the commentary, and further text titles giving detailed background information. Optional new CGI-effects shots have been added, which via seamless branching can be selected over the original 1964 model work. The new material obviously lacks authenticity, but looks about 1000 times better. Disc Two offers an abundance of extras including an amusing extract from Blue Peter (6 min) showing how to make edible Daleks. There is a photo gallery and some very poor quality Rehearsal Footage, but most fun of all is a 27 minute 1994 BBC spoof radio documentary which asks Whatever Happened to Susan Foreman?. Jane Asher plays Susan in an SF comedy as ingenious as it amusing and irreverent. This is a remarkable set, which belongs in any Who fan's collection.