The wife needed taking to a shop called The Range earlier (she does not drive).
So I had a mooch around and came across a packet of 3 sheets of Hoot & Loop for £1. Each sheet is 80mm by 190mm.
I reckon that's enough for 9 new Hook discs for my 2" inertial sander. An awful lot cheaper than from turning shops. May be worth a look if you have one near to you.