Wow, I've yet to see a price on them, but GW will apparently soon be releasing the Tread-head's favourite dream: the Emperor's Fist Tank Company!
As I suspected when I just flicked through the latest White Dwarf, the box in the image shows that it's part of the new Apocalypse range/scenarios/campaign/brand. At a full company of ten tanks, that would take a lot to shift and I can imagine it would be at least £250 (given that they're normally about £30 each).
It would be impressive to see one of those on the battle field, but I'd hate to actually come up against it!