Is there a program/service for tracking In-App Purchases discounts?

Question

In-app purchases

There are quite a few apps and services for tracking discounts on the App Store apps themselves. But none of them show discounts in in-app purchases (In-App Purchases) of applications, and after all, developers there also change prices or make them temporarily free and often silently, you won’t know until you check the list of in-app purchases or someone tweets .
Are there programs to automatically notify you about In-App discounts like AppZapp and the like?