reverse auction project: create account/login process

Dear all! We are a small Internet Consulting company, who needs help to setup the "create account" / "login" process for our project. Sorry for my poor English, my mother language is German. What our project is based on (installed): Joomla! 1.5.15 Reverse Auction Factory 1.4.1 (needs legacy modus 1.0) Community Builder 1.2.1 CBSubs plugin Our goal: setup a kind of [login to view URL] portal, but with completely different branches. In a first step we need help for a proper registration / login process. Basically it's the same process as in every freelance/auction portal. We would like to manage the users, their rights and the free ore paid subscriptions via the CBSubs plugin. We played a little with, but it seems to be tricky to implement it in the reverse auction factory. Example for a new user: usual registration fiels are no problem. But here the new user has to choose from "customer" or "contractor" (radio buttons). But once registered, he later can choose also the other subscription (upgrade to client or contractor, now for free, later paid). A client is not allowed to bidd, a contractor is not allowed to post projects (except he subscribed for). Later on, the users should be able to upgrade to some other (paid) subscribtions like "featured projects", "verified contractor", "top contractor",etc. We are looking for people, who have experience with such registration processes and, first of all, with the reverse auction factory and the CBSubs plugin. If the work is well done, we will post some other subprojects regarding our reverse auction project. If you have any question, ask please! Regards