Hello 'markerizza',
What you describe happens all the time. You cannot pay because the seller has no shipping fee specified for your country. So now that you have bought the item, he need only send you an invoice with the shipping fee (which the two of you agreed upon before you bought it). You will get the invoice in your regular email and simultaneously the item in your Purchase History shows the shipping fee. When that happens click 'Pay Now' and you're away. I'm sure the seller knows how to send an invoice, but on the off chance he doesn't, send him this link:
http://pages.ebay.com/help/pay/checkout-invoices.html
and all he does is enter the amount, Preview, and Send. (If he tries to use Recalculate, that never works).
Enjoy your new item. 🙂