AWS FW manager policy cost to manage common SG

Hello, I m exploring to use AWS FW manager to manage common security group deployment and other technical capabilities as well. When i was exploring the cost, i came across two data sources one is through blog post/AWS pricing page which says per policy (per region) it would cost customer 100USD and other source is AWS Cost calculator, in the cost calculator it resulting pretty much zero

what is the right pricing ? is it 100USD per policy/per region or the cost calculator ? and what am i missing in cost calculator or there no metrics added in cost calculator