Agreed about colour, I've been shooting with the K-5 for well over a year now and although with some custom raw conversion presets I can get close to the vibrance of the old K200D images, I can't make it
quite as good.
Interesting that you're shooting weddings with it, while elsewhere in the forum there are regularly threads with people insisting they need something even better (full frame, ten squillion point AF, etc) than a K-5 for weddings.
I think used prices are high because people like me can't quite bear to sell them - mine's been on loan to a friend for a few months.