Just back from the Sainsburys at Trongate, Glasgow. The full price is around £13 according to the shelf label; they're selling them for £3.57.
Also includes the Lemon/Union Jack special edition packets. Unsure if it's in other stores.
I realise Poundland does a 10 pack of Finish, but it's the "Classic" version of the tablets, not the All-In-Ones.