They usually do. Vets have overheads that they need to pay for their professional advice so unlikely to just write you up something. Unless you have already paid for a consult.
I get a prescription from my vet as I can obtain the medication I want way cheaper on the internet, but I when I order, I mark up the repeat prescription bit to the maximum, so I can get a year's supply on just one prescription fee (about £10 I think).
Our vet charges the same as Fatpiggy's does - £10. And definitely mark up the repeat prescription bit to the max as already advised. You do still save a fortune on lots of things this way.