Breeder or pet store for English mastiff?

I am looking to get an English Mastiff. I want him as a puppy as young as I can get him! I went to shake a paw and saw a beautiful one for $2099. Is that a good price? I was told to get one from a breeder would be really good as well. I am willing to spend some money but I do not want to be ripped off! What is a good price to pay for that dog? Also which is better to by from a breeder or a pet store? Thank you