I sold both of my CSPPC 233MHz 604e last year. The first one sold for $1,400 US dollars in less than 8 hours on eBay. Not sure what that adds up to in euros right now. The second one was part of a trade for other Amiga gear plus cash.
I would not be surprised to see prices come down a little, as more people consider getting faster G4, PA6T, or SAM hardware to run one of the PPC Amiga inspired operating systems.
But there will always be many people that prefer the original Commodore Amiga computers that will want this Phase5 gear that continues to become more rare over the years. Some people will sell cheaper than others, and some will try to price is like pure gold. Just depends on your luck when buying or selling this kind of gear.