Without knowing the condition, I can't say for sure, but I don't think it was worth what you paid (good shape is relative to the eye of the beholder). HOWEVER, who cares? It's just $13 and now you have 3 new super cool coins. Awesome! No shame in buying them. To be honest you probably would have never found those coins in circ. Well, maybe the wheatie, but it would have likely been in bad condition.
Nothing wrong with buying a coin. Myself personally, I love getting a great deal, but if it's a coin I really want, I'm prepared to pay pretty much whatever, unless I'm being blatantly ripped off. I've bought most of my cooler pieces. And you know what? Those coins that are cool, but aren't worth much, really you have to pay enough so that the coin is even worth the trouble of selling for the vendor. Especially on Ebay. I wouldn't bother selling a coin for 20 cents, would you?
I always thought those mystery auctions, though pricey, were an okay way to get started on a collection. When you're new, you don't have a clue what to go after; it's a starting point. Not something I'd likely go after now, unless there was something listed in the auction that I REALLY wanted.