You can purchase your own shop space in any empty shop by requesting it from staff members. See below for further instructions on how to use it. The shops are located in the mall, which is the large round building located in spawn city. You can buy/sell to other players. 

A Shop cost 10k eons to purchase. Contact Uzumi or MrDatsun to purchase one.

To Buy from someone's shop: left click the sign above the chest.
To Sell items: right click the sign above the chest. 

Iron Bank

You will find the iron bank (It's a wooden sign) located in the spawn on the arc in front of the mall. You can buy/sell iron to or from the server at a 1:75 Iron to Eon ratio. This enables you make money from selling Iron Ore.

Chest Shop Instructions

This is a shop that a player can set up using a chest and sign. You do this by placing a chest and putting the item(s) you want to sell in the chest. After that, place a sign above saying your name, the amount you want to buy/sell, the price, and then followed by the item you are selling, here is an example how it would be set up.

SIGN LINE 1: uzumi
SIGN LINE 3: B 10 : S 5

Line #1: The seller's name is Uzumi
Line #2: He wants to sell/buy a total of 64 of the item per sell/buy
Line #3: He wants to sell the item for 10 eons, and buy for 5 eons
Line #4: The item he is selling has a data value of 5.
[Note: For easy memorization, always think of it as from the consumer perspective. The Consumer [B]uys from the shop, the Consumer [S]ells to the shop]

 You can either insert the name or the numerical value of the block, but for items that have multiple types with the same name the # is required.
Here's a list with some of the values.