Consider using Dwolla.com instead of credit cards. No transaction fees at all for < $10. And it's run by a brilliant entrepreneur determined to disrupt the credit card industry. Cutting edge stuff.

+1 added here:

https://github.com/whit537/www.gittip.com/issues/65

The basic Gittip roadmap is to get the full circle working once with the most common case (credit card in, ACH out), and then iterate from there.