Invision Power Board custom mods

Hello, i need following thisgs: 1) i need a person that know how works IPB and worked already on this software before 2) Actually this software has one functionality that let people sell over the board their DIGITAL FILE. I need to expand this feature adding possibility to every people not only to sell file but also to sell other type of good: example: services, objects and so on... 3) i would integrate IPB login system with account fron a custom CMS. I mean people registred on my custom CMS i would like they can do login with the same user and password. The point 2) is the most important anyway and i need a real quote from someone can in real do it and that know IPB already. Thanks