[Note: This mail relates to a discussion on one of the boards, where an estimate at the cost of hiring a Faceless Man was made based on comments by Littlefinger. Martin responded, when presented with the estimates, that Littlefinger's statements were taken too literally.]
The Faceless Men don't post a list of prices on their door. The way it works, you go to them and tell them who you want killed, and then they negotiate the price. The prominent the victim, the more difficult to get to, the more dangerous for the assassin and the guild, the higher the price.