This site is often searched for is the Store Kit and in-app purchase tutorials.
There is a very straightforward tutorial for store kit basics that can be found here: Using Store Kit Framework
Yesterday, I found this excellent list of resources on In-app purchasing. Which lists the Apple resources, and others that describe the process of implementing in-app purchases. If you want to know everything about in-app purchases you’ll find it in a resource on that list.
Included in the Under The Bridge list are a couple of step-by-step tutorials from Mugunth Kumar:
In App Purchasing
Enabling reviewers to use your in-app purchases for free
Please post any comments below, thanks.