I bought the original Evercade when my fellow YouTubers were singing its praises. The games were all $20 a piece. I just looked at Amazon and almost all of them were either near or $30+. Castlemania has the games at a much better price. You can see what they have in stock here.
One anomaly was Toaplan Arcade 2, which was $20.
It appears that the new games are at the $20 price point on Amazon.
Inflation was inevitable, so it does not surprise me that these cartridges are increasing in price.