I state that "internet payments are also excepted (please contact me for details)"

I then mention that "I accept PayPal without a credit card" in my details when I send the invoice. Probably also a violation, but if it is and they stop me, I will just send a personal email.

Ebay is free to do whatever they want as far as fees are concerned, but they are not getting any more from me by forcing me to use a CC.