hello drupal forum,

it's my first post here so i hope i'm posting in the right place....forgive me if not....

i'm planning on a new site and still got some headaches, one of them is as follows:

on the site users can sell their own products. on purchase of a user's product the $ minus a certain percentage (to the site) will be credited to his online bank account. given a minimum amount the user can transfer his winnings from there to his real bank account. first thing here is safety, what can i do to keep the database where each user's credit is stored REALLY safe? and how can i do the (safe) transaction? can i use the methods provided by the used e-commerce store module (ubercart or ecommerce) like paypal, etc. to transfer money from the virtual bank account (which in real is just the site's bank account) to the user's real bank account? do i need them? in fact it's just a bank account to bank account transfer, no need for paypal in between or any credit card stuff, but of course it needs to be safe too.
any idea, tips on how to realize this kind of stuff?

thanks a lot,

dw