but they are good farm vets though - why are they so greedy?
Because of pet insurance and the way farming works in this country, is why.
In a farming community, a practise that wants to do farm vetting has to charge at a level that farmers are willing and able to pay. There's no veterinary insurance for livestock, so we have to pay the fees out of our businesses.
Now that pretty much everyone has pet insurance, however, the small animal fees have gone through the roof. I'm sure that side of the business will help a mixed practise to offer a sensibly-priced farm tariff.

As a farmer, I am of course grateful that my vet can manage to offer me a good range of services at an affordable price.

And I see that, although pet owners are charged a lot for the services they get, the practise reinvests and has an impressive array of equipment and procedures available for the treatment of small animals.
But there will always be cheaper options for a pet owner, and if the equation doesn't work for you, then you have to vote with your feet.