150 - Jackson vs 185 Panther = cost difference 23,33%
But Armor difference 130/60 vs 260/90 = 100/50%
Health difference 640/960 = 50%
This is not a balance
What about you compare their range also? Or their moving accuracy? Or Jackson HVAP ability?
Btw you have a funny substantiation. "50% more armor means the tank is 50% more effective than the other tank". Welp, a Panther will still get penned by a vet 2 SU85 or Jackson HVAP shot in 100% of the cases.