My vet charges £10 for the first item and £6 for any others. I get medication for my cat and buy from Viovet online, they are great, next day delivery, really easy, just scan the prescription and away you go.
Some vets do the prescription on repeat of say 3 months so you can just apply to the online chemist monthly and pay monthly, others like mine just do it as one bulk prescription so I get 3 months medication at a time.
It works out for the heart meds my cat takes that I sort of get a month free every quarter doing it online.