I'm not really sure what are you requesting. Anyway, if you want, together the image and the cost, more characteristics (items in inventory) you can add them to the list if lists and access them in the same way than for the elements 1 and 2 of each item.
Then, when a user buy an item, you will have to subtract -1 to the inventory number of that item. Other thing to be considered is where are you going to store that data if you want it to be consistent when you close and reopen the application. For this it could be a good option tinyDB.
Take a look here:
App Inventor 2 Book: Create Your Own Android Apps
And in the community you will find some topics similar to yours.