Cancel their bid:
http://offer.ebay.ca/ws/eBayISAPI.dll?CancelBidShow
Add them to your blocked bidders list
http://offer.ebay.ca/ws/eBayISAPI.dll?BidderBlockLogin
Set your buyer requirements in My Ebay, Account, Site Preferences to block bidders who are in countries you do not ship to. While you're at it, also block bidders who do not have a paypal account, have 4 or more policy violations in a 6 month period and who have 2 or more unpaid item strikes in the past 12 months.
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Non payers should get unpaid item strikes and be added to block bidders lists. Period.