The price has now been reduced to £249.99, i'm not sure if the price has been reduced to shift them or if it's because the price of larger tablets is falling in general.
They are also offering one for £17 a month with some Smartphones:
http://www.virginmedia.com/shop/mobile/showtime.html
I wasn't sure who manufactured these, but this is only available with Samsung Smartphones, so maybe this is an indicator??