Yellowstone is the Earth's most extensive thermal area and is home to more than 10,000 natural springs, fumaroles, mud pots and geysers than those found in the rest of the world put together. This fascinating documentary takes you inside one of our world's most amazing natural wonders and focuses on the variety of different species that live there.
Might be store specific but cheapest I have ever seen it, even second hand it rarely goes below £9.
Is meant to be a very high quality Blu Ray (haven't watched it yet to test for myself!). Can post receipt if required.
Edit: Found this in the Bromley store, it should be nationwide and will depend on stock but I imagine nearly every large store will have at least a couple of copies