Tutorial about in-app purchase plugins like prime31 or soomla ?

i am looking for a plugin for in-app purchase system these days, and after couple of days searching i found some plugins like prime31, soomla &… but problem it is,
there is no good enough or step by step manuals for them. and for guys like us who didn’t use purchase before is some kind of hard to make one without a manual and by just a example project.
and i wanna know there is any chance for us to learn these plugins by easiest way like complete video tutorial or something like that?

Soomla recently went live with video tutorials on how to get started with unity3d-store.

unity3d-store with Android:

unity3d-store with iOS:

First, Prime31 StoreKit plugin and Soomla do not belong in the same category. Soomla is more of storefront all in one solution. I have not used it, but I can tell you it is worth considering mostly if you plan on having an in game economy.

If you want to let users purchase some simple “unlocks” or coins in game, you can easily implement your own with Prime31 StoreKit.

I have experience with this plugin, and although it is not as easy as everybody will make you believe, it is also not that difficult.

The nice thing about it, is that it is just a wrapper for Apple’s In App Purchase process - so you can get read the Apple’s IAP guide, and Prime31’s StoreKit docs, and dive right in.

In addition, this forum thread may help as well as this answer