Floor and discount tiers
AWS Savings Plans and Reserved Instances cover compute. API Gateway itself does not have a direct savings-plan equivalent; EDP and PPA discounts apply at higher commits. Azure's MACC and EA models discount cross-product. Apigee Subscription floors are negotiable.
Avoiding overcommit
The trap is committing to a call-volume assumption you will not hit. Build the commit around the lower bound of forecast, not the centre. Ask for true-down clauses, not just true-up.