
Puts me in mind of a well-known breeder who managed to get her hands on a 'top stud dog'. In truth, as is often the case, he wasn't being used as much as his sire whch may, just may, have been part of why she was able to buy him. However, I took one of my bitches to him and she missed. He missed shortly afterwards to another visiting bitch and over time, it became apparent the dog was firing blanks. He never sired a litter with his new owner. Not to say your situation is the same but I have to wonder why anybody with a stud dog would necessarily sell him, to a novice at that. He may not be what you hope he is.
There's another thing worth bearing in mind re buying a 'stud dog' - so you are going to use him on your bitch. What then? You might be lucky and get interest from others (is he going to right for all the enquiries you might have?) but once you have used him on your own bitch, unless you do more than the one litter from him, he will become a passenger. Given once you do have a litter, you'll want to keep something from that litter .... it's amazing how quickly numbers add up (been there!).
For me, it makes more sense to use outside stud dogs, unless you happen to have an outstanding male in one of your own litters, to keep and show.