Heavy price to pay

I had to change vets recently due to having no transport to travel to the practice I have used for 20 years, which is 10 miles away.
The medical records were transferred for my dog Millie who has a heart problem. She has been taking Fortekor 5mg, for which I have been paying £26.54 for 28 tablets. After a consultation (as a new patient) I was given the usual tablets but was charged over £42 for them. When I questioned the price difference I was told that this was the price they were charged from their supplier. I explained I would find it difficult to afford this price and she then said that perhaps they could do a 'deal' and suggested £31.50.
Is it a common thing for medication to vary so much in price between different vets? I find it quite shocking.
Deborah Lyons, Leicester