How To Create a Player Chest Shop
To start, place a chest on the ground.
Next, place a sign 1 block away from the chest.
For example in this screenshot it has been placed above the chest.
On the sign above the chest, write a format of the following:
(Fig 1) This format is an example for buying and selling an item.
(Fig 2) This format is an example for just selling an item.
You know if you have created a shop successfully if you get a message along the lines of "Shop successfully created!" in chat.
If you are having issues what to call an item on the sign in your shop, use the /iteminfo command to figure out what the name of the item is and also what to put on the shop sign, as seen below.
In this example Dirt is being used the item and the name of the item to be used on the Shop Sign.
The first line will be your username.
The second line is the amount of items to buy or sell per transaction.
For example in Fig 1: Buying 1 Diamond for $10 and selling 1 Diamond for $5
The third line is a combination of buy and sell prices. You need to have a price indicator (like B - price that will apply to items bought by users and S - the sell price) near the price, the prices are separated by a colon :
The forth line will hold the id/name of the item.
Note: If you get stuck with this you can write a ? on the sign and the item will be auto filled with the one from the chest or you can click on the sign with the item afterwards.