How to use chest shops:
Sign format for making shops (signs have to be on a block touching the chest)
Line 1: You can leave this blank it fills in your name automatically
Line 2:Quantity that you can buy at once
Line 3:Buy price:Sell price
Line 4:Item ID (full item id list available in a reply to this post)
Buy Price= how much they buy it from you for
Sell Price= how much they sell it to you for
Note: You don't have to inclue both a buy and sell price, you can just do one or the other
Left click to buy, and right click to sell
In my example, you can buy 16 (quantity) wood (item id) for $64 (buy price) from me (player name from line 1)