I spotted that Wickes are doing a 450litre compost bin for £9.98. I cant find it on their website, but there were 3 in Milton Keynes store (last week) and 1 in Bletchley (that I took). Shop code - Composter 450L , 159337
It is the Large square type that has a "door" on each side to allow easy access. Also has an "automatic" lid which makes one handed loading a doddle. May be a bit too big for some gardens, but seems a snip at the price. We got 2 that are identical a little while ago from B&Q (for much more money :(
). These are usually nearer the £50 mark and more.
** EDIT --- it is the same as this one on link -- http://www.keengardener.co.uk/product/view/1127/composter-450-litre.rails