Ask HN: Facebook Credits Alternative?

Hi All, I want to make a collaborative website that uses credits (purchased with cash) that can be redeemed at any time for a small fee (perhaps 10%). So far all I can find is Facebook Credits, but they charge an exorbitant 30%, probably following Apple's lead. I would have to charge something like 40% just to stay in business and I just don't see users wanting that. I could easily implement something like this myself but would have trouble sleeping at night with hacking so prevalent. I think that what we are really paying for is security, at least the sense of it, because facebook can provide a privatized form of FDIC insurance with its billions and billions of dollars. We are basically paying them protection money. So my question is, that since there is a nonzero probability of any website being hacked, perhaps we have been looking at this the wrong way. Is the main thing preventing websites from using their own credits - a lack of insurance?