This was my first addon purchase for XenForo, after searching for quite some time. I did a lot of research on shop/item systems, and DBTech's is honestly the best out there right now.
It was extremely easy to configure and set up, and the language is simple to understand for myself, a native English speaker who does not know too much of XenForo's systems or code yet.
I also purchased DBTech's Credit system, which implemented into this addon with pretty much 100% ease.
I would definitely recommend you check this addon out, along with all of DBTech's other addons!