Mick, you don't want a 2" wide collar on a dog with a neck that size, I'd have said 1" or at a push 1.5" wide, but honestly, not a 2" one, the dog won't be able to lower it's head.
Is it for a terrier?
1" would be £10 - £12, 1.5" would be £12 - £15, depending on wether you wanted steel or solid brass fittings.