Just found these Antec CPU coolers at PC World reduced from just shy of £40.
A quick google and I believe this is the cheapest price currently available for either of these two coolers.
The Box is £28.99 and the Flow £37.17 at Amazon
Box £25.99 and the Flow £26.30 at Dabs but need to add £3.99 p&p
I don't usually buy from PC World but after the last PSU sale they had have been watching out for items they put on sale/reduction. With the reductions the price of the items drop to worthwhile if you are considering a specific item, imo.