What you will need:
Chest, Sign, Redstone and the items you wish to sell or buy.
Place chest down with the quantity of the items you want to sell at one time
e.g. For one Sign click, the buyer will get 5 of the items.
Place the Sign and type:
Second row: Name of item
Third row: Quantity sold
Fourth row: Amount sold for E.g... $5.00 each time bought
Get the Redstone in hand and left click the chest and then the sign. The[Buy]or[Sell]part should turn blue
Put all the items in.
[Buy] [Sell] Colours
Blue = In stock
Red = out of stock, Chest is full
Grey = Try again!