I was hoping for an operational upgrade on last saturday's JFK-GVA, but the plane wasn't full at all. But when asking at the check in, the woman told me that she could upgrade me for $333 from Y to C. Since it was a very cheap ticket I got, and was feeling very tired of Y, I decided to buy it, even though the flight is not so long. It was the first time I ve been told I could upgrade for $300, which I think can be a very good deal, especially if flying from ORD or LAX or other long-haul destination. Has anyone other experience with this ? Is JFK the only place where they do it ? Thanks in advance.