You are looking for Traditions Buckhunter Pro in-line pistol. They came with barrels ranging from 9-15 inches. I looked around but couldnt find any, hell wallyworld use to carry them. I think they sold for $200-300 depending on finish and size. Look around, might find one for a decent price.

Also, forgot to add; if you have an Encore pistol or a Contender pistol from T/C, you can have a custom barrel made. Cost is around $300.