Ummm... helpful to know who for sure took your stuff, and what they took. Also helpful to understand exactly what you are offering here... are you saying you will pay someone to get your stuff back from "porthos or someone"? Or are you asking "porthos or someone" to haggle over the price to get your stuff back? Also, if it is just money, you will NOT get it back.. there is no way to directly exchange money between players.
To be honest, most people who steal (from your backpack) or rob (from your house) don't keep track of who they steal what from (unless it happens to be a very LARGE steal--I have a feeling this is not one of those times). So much gets stolen constantly that it would be nearly impossible, and a waste of time trying to keep track of every bird feather that changes hands.