$900 is far from being unheard from, (probably better if I didn't tell you how much I spent on snakes last year), yes it is overpriced but it is a pet store so the pricing will be higher than buying directly from a breeder.
You would be surprised the amount of people spend for a pet, and while most would not question spending $1000 for a dog they always seem shock if you tell them you pay that much or more for a snake.