This mod adds one node and a privilege.
The node is a "store" where one can buy a single itemstack for a different itemstack, there are no limitations as to what can be used as the payment or the product being sold.
A player needs the autostore privilege to dig or place the node.
Once an unconfigured store is placed right click on it to open the formspec and set what is being sold and for how much and give it a name, then click save.
Once the store is saved any player can buy the items.
The beautiful thing about this store is there is no inventory to maintain, so once it is setup it will be able to sell the items forever.