Just found this Gro Hush is half price online direct on The Gro Company website - seems to be up there with the cheapest at £14.99 - but then they have a 12% voucher for mailing list sign up. Free Delivery too.
Usually £24.99 in shops (altho looks to have been cheaper on hotdeals from time to time)
This was a god-sent for our first born so been on the hunt for one for a while!
(First post, hope its all done right)