There is likely several dynamics at work. One of the little known issues with the dealership closing was the transfer of autos to the dealerships remaining open and the debt of those autos. From what I was able to ascertain, there was a deal worked out where the outstanding debt could be transferred (ie if a dealership owed 20k to the factory for a car it could be transferred to the gaining dealership) but that deal only covered 2009 model year vehicles. As a result, all the dealerships were REAL motivated to liquidate their existing "older" stock. There was a dealership here locally that had something like 14 xfires, and they were letting the 2008 versions go for around 28K for the roadsters and less for the coupes. This likely got the price point down to where they got sucked up. There are only a couple left here locally. I ended up getting mine from the east coast and having it shipped to get the spouse the color combination she wanted. The good news should be that now that the stock is basically gone, I would expect the price to stabilize because they will be harder to find if someone really wants one.
Don't expect ours to ever be for sale, wife love the Xf more than she love me!

Just my nickles worth!