We wrer given such a wide range of prices, it was unbelievable

. From the very reasonable flat 500 Euros to 1500 Euros plus 50 per living pup

(we had 9 pups last time!). The argument made for some of the fees was that it was the price of a puppy - well, maybe in their country it was, but certainly not here in Bulgaria

.
As someone has already mentioned, there are no rules governing this fee - a price is given and if you don't like it, use a different stud. It's as easy as that.