Google today dropped word on the developer dashboard that the price-range for in-app purchases on a given app soon will be listed in the app description. The change takes effect Sept. 30.
Basically if an app has in-app purchases or subscription rates, you'll be able to see the ballpark cost first thing and not get blindsided later by, for (extreme) example, a free app that for some reason charges $20 later to do something. (And for parents, this definitely is a good thing.)
Here's the announcement from Google:
Price ranges for in-app purchases Beginning September 30, 2014, all apps offering in-app purchases to users will have an "In-app purchases" price range displayed on their detail page on Google Play. Price ranges will include in-app products and subscriptions.
If any of your apps offer paid in-app features or subscriptions, go to your app's In-app Products page to review the prices and publishing status of your in-app items.
So look for that shortly.