I'm pretty sure this type of business is considered a "payment aggregator" by merchant account providers and acquiring banks. It's usually difficult for a young startup to get an acquiring bank to underwrite such an account.

You can find some more information on payment aggregators here: http://www.braintreepaymentsolutions.com/blog/high-risk-mech...

You should also try out Amazon FPS: https://payments.amazon.com/sdui/sdui/helpTab/Amazon-Flexibl...