Economy, what's this?
Currently we have none.
Limitless resources are the biggest weakness.
My solution:
Resources are available only in certain locations.
Gold - nearby Redding, Uranium - Broken Hills etc.
When you are travelling thru Wasteland you can encounter the terrain with single vein.
You can place there a tent or house, the vein remains active.
Every vein has limited amount of resources - generated randomly.
With high Science Skill you can examine the vein.
This will provide the new item to trade - map with rich vein will be valuable.
Public mines can remain, but with very limited resources.
The same solution could be used for plants.
Single plant will give you only 20 pieces, but you'll be able to respawn them using the brahmin dung and/or water.