While I find a working, updated shop plugin, Trade signs have been enabled to allow you to buy/sell/trade and a market will be built. Here is a tutorial on how to use trade signs: 
http://ess.khhq.net/wiki/Sign_Tutorial#Trade_SignI can't seem to find an updated shop plugin that has a feature that I really want to keep the server balanced; I don't want the shop to spawn in extra items that didn't exist in the world in the first place. For example, if you mine a stack of cobblestone, you had to take that from the world and if you sell it to the shop, the shop should now be able to sell 64 cobblestone back to players. I can't seem to find an updated plugin with a player driven economy, though I did find one called Finite Global Shop that has all the features I want, but it didn't seem to work when I put it in the server because it wasn't updated. Every command returned a global error.
but anyways the CUNTS MALL is open at spawn and if you'd like to have a place to sell to other players in a neutral territory, just ask.