Clan payment system

I am looking for a clan payment system for my customers. I run a game hosting company and some of my clients would like to be able to add a link or batch of code to their site and have there members contribute straight to there bill vrs. collecting all the donations and then paying us. If it requires code on clients websites code must be easy for them to add and customize visually. I use modernbill V5 to automate my billing. So knowlege of how it works would be a plus on your side. I am looking for quality work and will pay for it. The job won't simply go to the lowest bidder, but the person I feel can provide the best work at a reasonable rate of course. Please provide sample sites and or projects you have worked on. Or if you feel so inclined a sample of working script. I will use escrow for payment if requested. But will not make payment to freelancer until work is completed. Thanks.