Have you looked at the example browser in C3? You can search Dictionary in that. Not sure if those help.
I'm not sure what approach you're wanting for the shop. What you want to look like.
Because you could also use Arrays for this kind of thing.
It may be helpful to use the array/dictionary editor, then load that file into your object with Ajax plugin. If you're not doing that already. So that you can have a list of all your items data.
Like, what kind of ID do you want? You could use numbers or words.
And what values do you want attached to the items?
If you're just wanting an ID as a number, and then the value of the id being the name. Then you could just use an array.
e.g. 0 = sword, 1 = shield, 2 = helmet
Then if you're looking to have text to set the name of an item. Then you could have an action that "set text" to: array.at(1), which would show the name "shield"