Tom;
Just to chime in and add that I would also find internationalisation of billing currencies a very compelling, indeed vital, addition to the Reselling Services feature set. The fact of known, fixed, monthly payments is a substantial selling point; having to then reveal to a potential client that, in fact, the payment amount is only fixed at the dollar end and the amount that will be actually debited from their card or account will vary according to the vagaries of the exchange rate, can only weaken the sales pitch.
Logically, of course, it might not make any difference — but these sorts of decisions are not always based on cold logic. And the kind of additional complexity (however minor) that the currency issue introduces is bound to register in the customers gut, where the *real* decisions get made.