[KaVir]

Well said. So, back to the payment system:

This is also very similar to Hephos's suggestion, except that he's separated "Payment and/or donations accepted, not rewarded in-game." into "donations without rewards" and "In-game merchandise sold". Personally I don't think such a distinction is necessary, as it's not really very important and is the sort of thing that could be mentioned in the text area.