$80-100 is a fair price.
The harder part is getting them to match. They are not all built to the same specs and come in different widths, heights, and shelf configurations. Some need the door latches rebuilt.
If you plan to repaint them, best buy 2-3 so they can be all in a row and look nice. Do all your welding or customization first- I would suggest mounting pegboard on the inside of the doors with shallow hooks to hold things like saw blades, card mounted new stuff, other shallow items. If you really want to go to town, you can put in shallow shelves on the inside of the doors for solvents/spray cans depending upon the internal dept of the shelves.
I would gladly buy three of them now if I could find a matching set.