This is a fairly straightforward question. In The Two Towers, it is revealed that Sauron pays his armies. When Merry and Pippin are abducted by Orcs, the Orcs argue about what to do with them. An Orc from Mordor suggests bringing them to a nearby Nazgul, and another Orc scoffs, saying:
"Maybe! Then you'll fly off with our prisoners, and get all the pay and praise in Lugburz [Lugburz is the Dark Tower of Sauron]..."
-The Lord of the Rings, The Two Towers, Book III, Chapter 3: "The Uruk-Hai"
This made me wonder how he got the money to pay them - did he use magic to make it appear out of thin air, or is it the accumulated rewards of centuries of pillaging, or does some sort of commerce, trade, and enterprise take place in Mordor? For my actual question, I'm only asking about the business, commerce, and trade aspects of this issue (not about making money appear, or pillaging, or even levying tributes and taxes on Mordor's allies and neighbors).
So again, does Mordor have a true economy, i.e. businesses, trade, commerce, shops, commercial manufacturing facilities (i.e., not just slaves making weapons, etc), and so on?