Without guarantees from the original breeders and not having him proved out yet he is not worth more than a regular albino.
I believe the store is taking you for a ride.
To produce an albino pied you need to already have an albino pied to pair him with another albino, DH, het etc.
Now here are the issues
Because of the odds not many breeders have produce Albino Pied
Because of the price that an albino het pied would fetch (several thousands) a breeder is not likely to wholesale them to a pet store which in turn would only sell it as a possible because of the lack of paperwork.