Just don't buy it, there are many ways to play the game. No one asking you to buy him. He will be free eventually when he is old enough, it may take months to get him but it's how the game work even in CN.
Angel Konan, Reanimated Deidara, Reanimated 2nd and 3rd Hokage, etc... all has price above 10k cp in CN.
So instead crying over his price, just don't buy him. You got the idea, this is how it work from now. At least until CN change it our version won't change how the game work.