We bought two of them last year. One off a market trader (pictured, a monkey), but it was a bit small. And the other we bought at a local bath/bedding shop. It was bigger and of better quality, and was a bumble bee. They are nothing more than hooded beach towels so you you'll probably have better luck finding them in the spring or summer months.
PS: we did see some in Mothercare last year (hooded beach towels), but they were an arm and a leg. The ones we bought were cheaper.