This price equals ~
BTC2.5, which is on par for historical purchases for this series coin, but is a bit higher than what these coins are selling for in the Collectibles section of this forum. This coin has an error on it, Casascius is spelled "Casacius" so it's a bit sought after.
The more rare 2011 series 2 Casascius coin is significantly more rare, doesn't have the error, and should command a price of at least
BTC2.5 and higher.
I think your point is that the price is high, and most Casascius coin offers on eBay are extremely high, not realistic high, but those are just buy it now prices for ridiculous amounts. It sounds like this one was a proper auction. I'm glad to see these coins trading hands outside of Bitciontalk! I bet someone on this forum was the buyer and the seller!
TL,DR: This>>> Interesting to see non-collectors discuss collectors items/their premiums.