Hmmm...
That post was made 16 years ago, Mr Cuttsie...
... so even if they're still there I suspect they'll be charging a bit more than a fiver.
I've always used Jepsons on East Bank Road, but not had any for a while so I don't know how much they are these days (but they were much cheaper than Halfords).
https://www.jepsonandco.com/