Personally, I'd buy it from the mint. I do buy some coins and sets on
ebay, but I've just never been a fan of auctions where you don't see the actual item you are purchasing. That being said, he appears to be an honest seller, judging by his feedback. I guess the question is, is it worth it to you to pay an extra $5 (shipping costs) to get it from the mint, where you know for sure they will replace the set if there are any flaws with the coins.