Originally £21.49 but you can get them on eBay for slightly cheaper.
This is the largest (suitable for up to 50kg dogs) blue model.
Pets at home currently have 50% off which makes it £10.74 but only when you reserve and collect and ask for the reservation order, Do not just turn up to the store asking for this price because they are still £21.49!
I just bought one from the Blackheath store and grabbed the last one. Stock shows beckton have one in stock too but I haven't checked anywhere else.
Please note it is only the LARGE one which is half price.