We are a new b2b web-based office-management ASP in a niche market. We want to provide our customers with the ability to charge their clients' credit cards through our website (credit card billing is only one of several office-management features we offer). I think this means we need to become (not use) a 3rd-party merchant. Since we are in a niche market our volumes will be quite low.

Does anyone have any recommendations on how we should best proceed to be able to offer our customers the ability to charge their clients' credit cards through our website?

Thanks very much for any tips.
-Buck