A double square bridge is about $15000 and it does depend where and how you buy. If you buy from a shop in the U.S. you'll need to add more than $1000 for tax. If you go to London to buy, you wait 6-9 months and have to pay cost of shipping to one of their importers in the U.S. But you have the opportunity to add little things to rifle that can quickly raise the price well over $20,000.
Anyone interested in contact names, numbers and emails for the London shop, send me a PM with your private email address and I will forward you the info which includes all of the add ons you can pick if your pockets are deep enough!