As of right now there is an issue with the “Make In-App Purchase” and “Read In-App Purchase” nodes. It seems these issues have been around for awhile and there has been no mention of resolve.
Make In-App Purchase: Always consumes purchase even when “is consumable” is not checked.
Read In-App Purchase: Always fails even when data is properly entered. A fix has already been provided in the answerhub but requires compiling a custom version of the engine.
These issues make it difficult to implement one-time purchases for projects, and properly displaying prices of purchases.