need xenforo forum addon that addon work for me like!

need xenforo forum addon that addon work for me like! user list any item there and other user want to buy just click buy now when user click buy now then user take the item .after pa_id 3 way conversation start with admin buyer and seller add-on which is pretty much a 'button' that runs a php file/function/callback. This file must be able to get custom user field data, as well as the members' current ID, and whether or not they are in a usergroup. (I will personally use this to include another php class, and run a function which will add the corresponding data to my table.) If it's not too much of a hassle, I'd also like to be able to somehow communicate a response through the file that the button calls, ie Button (on a page) ---> (middleman) File ---> Information Processor Information Processor --- True/false---> (middleman) File ---> Page I don't really mind if it sends this data long to the page via means of $_['GET']. Any xenforo wizards willing to help?