I've mentioned this across multiple collector threads. Values are also driven by equitable events. Collections are ran as a loss leader that push losses against huge tax hits people have for various reasons. One of the reasons you see people grab a lot of cars in a short period of time, also selling them in short periods of time. As economic booms continue, prices will rise as people look for different area's to place cash and adjust their tax hit. Money is very cheap right now, plenty of collectors building collections on cheap interest rates.