Where is common sense rules of supply and demand, or economics?
All price unreal, caotic.
The retro Amiga community has only 3-4000 active members on the world. How may 3000 member cause big demand, and high prices?
It is essentially: The lowest price the people who are selling are prepared to accept combined with the highest price the people who are buying are prepared to pay.
So if someone had enough boards to satisfy all the demand and was prepared to sell them for $1 then that is the price. If you have the only one then you set the price, but you may not sell if it's too high.
With equipment like this there is no real value, so it will peak at a certain point where desirability and disposable income is at it's highest and then it will taper off. In fifty years time we'll be dying off and nobody will care about it enough to keep the value high.