Selling to someone in another country

Now how do you like to see this sequence of events?

* CLEARLY my ad says no non-US/Canada bidder.
* Some overseas member in Asia asking u whether u'd let him buy moments before the auction ends.
* He's got great feedback, so you provide him with details and how you might entertain a bid from him.
Then when the auction ends someone with zero feedback from that same city places a bid.
* member with great feedback then emails you immediately saying "Oh I missed the bidding but lets make a deal"

Now I need to relist the item and pay another $6.

So the question for you guys is, how do you prevent a joker-scammer from winning the high bid in an auction??

Thanks for the advice, the "wanted Ad" does seem to be a great idea. Cheers.

Another "incident" related to international shipping

I had another ad that specifies "Ship to US Canada Japan" only.
Winner still bids on item despite my email caution of voltage and expensive shipping.
Winner wins auction, then says "out of town, will deal with u when I come back." THEN asks me to ask manufacturer for circuit map to modify voltage.
I did that for the winner as a courtesy.
The winner requested SURFACE SHIPPING (he selected Fedex economy when bidding!) to Europe.
I checked for surface shipping but found out amps too heavy for USPS (70 lbs limit) instead of FedEx Economy.
Winner asked me to dismantle amps to "Make weight"
which I refused after checking how vulnerable amps would be if dismantled (LED and switches and meters).
Lost communication with winner for a few days and then I pinged him with email that asks " am wondering if you would want to proceed with a
straightforward transaction or you'd like to back out. Your response is appreciated..."
Then very shortly afterwards I received a rude nasty-gram accusing me of not wanting to sell to him.
I am not going to post a negative feedback on the guy cos I think he will just sandblast me with negative feedbacks.