This often happens on eBay. People get caught up in the bidding. I had one guy tell me he bought the cheapest one on eBay, of course he quickly ignored my asking him if he ever heard of buying somewhere other than eBay to get better pricing.
What happens on auctions is low value items that appear the same as high value items get way more money. A lot of people have no idea that Apple changes the MBA, the difference between SSD and HDD, a 2.13 or 1.86 is all they see - sometimes not even that.
Someone who doesn't know anything will see an SSD model top of the line brand new sell for $100 more than they can bid on the lower model, not realize the differences, and pay way more than they would even brand new from a discount electronics chain.
It's really sad!