NPC's are people too! Give them the resources to run a business!
This is a sample of my fully modular "General Store Goods" file pack available at http://www.heroshoard.com/ This sample includes an angled display shelf, 3 modular shelf inserts, and a cooking pot.
The full version has 2 display shelves, 1 display case, 23 shelf inserts and a ton of stand alone items as you can see from the pictures.
Monoprice Maker Architect 3D