AutoPrice Bukkit plugin

A shop plugin with GUI and dynamic prices.

Features

Highly configurable.
Good default configuration for lazy server owners (like myself).
Designed to require minimum input from server owner.
Commands and GUI (Graphical User Interface).
Prices will automatically be adjusted based on supply and demand of each material.
The shop can be accessed by any player at any location.
The plugin keeps track of each material's stock, players can't buy more than has been sold.
Item damage/condition is considered in price paid and stock increased. For example selling two items in 50% condition will earn you total 100% of normal price and add total one item to the stock.

Known limitations

It takes a while for the plugin to learn the true value of each material.
The plugin automatically saves the changed information to configuration file, so it's best to stop the server if you plan to work on the configuration file. You can however try to edit it quickly and use /ap reload.
Materials in shop can only be rearranged by editing the configuration file. Renaming an item will however move it to the end.
Each purchase is added to player's inventory as a new stack.
Does not support the wildcards in permission nodes of PermissionsBukkit

Shop GUI usage

The shop GUI looks like a chest, but there are couple differences. The top window shows the items you can buy and bottom shows items you can sell. When hovering over any item, information about that material is displayed (price for example).

The amount you sell/buy depends on the type of click

Left click = 1 unit
Right click = 4 units
Shift + left click = 16 unit
Shift + right click = 64 units

To change page on top/buying part click the empty slot

Left click = next page
Right click = previous page

Requirements

AutoPrice is just a shop plugin. For AP to work you will also need to install an economy plugin like Essentials economy. AP does not directly support any economy plugins so you need to install Vault that works as an adapter between AP and the economy plugin of your choice.

Infinite stock

Here's an example how to configure an item to have infinite stock. Here the purchase price is 0,55 and stock is infinite. The plugin normally adjusts prices based on purchases and sales, manually adjusting stocks can cause issues with dynamic prices.

      APPLE:
        baseSalesPriceForPlayer: 0.5
        mainMaterial: APPLE
        subMaterial: 0
        stockPerPurchasePrice:
          0,55: !!float 'Infinity'

Questions & answers

How to get stock?: Let players sell stuff (prices will slowly normalize) or set stock manually in the configuration file (but don't expect the plugin to learn the value of the item).

How to increase the prices?: Let players buy all the stock and wait for the prices to increase. If all prices raise too slow, decrease updateIntervalTicks in the configuration file. Low supply & high demand = high price.

Why does the sales price of an item drop to 0.01 as soon as I sell the first one?: Cause that item now has sales but no purchases. High supply & low demand = low price.