Wendersnaven.com (a resource for nwn2 builders)

From the official documentation:

"Stores are only accessed through script in a conversation – they are not objects that the player can detect. Stores have blueprints just like other types of objects. After you create your store’s blueprint, place it on the map normally. It is generally best to place your store next to the NPC. Check out the Sample Module for an example of a store."

Stores are usually started from a script attached to a conversation using the "ga_open_store" script. Place a store in the area and use the tag for the store as the first parameter.

Item costs 

The nMarkUp and nMarkDown parameters are for when you want to adjust a store's buy and sell price due to a plot driven situation or some other condition. Generally, you can leave these at 0 and 0.

You can create your own stores based on the pre-generated ones by right clicking and choosing copy blueprint. Note that when you do this, the seling and buying percentages are both 0. If you don't fix this, everything in your store will have a base cost of 1.

Thanks to seryn for doing the leg work to figure out that the OC uses a standard sell price of 100% when players purchase items and a 40% of sell price when the store buys from the player. These options are located in the properties window of the store. This is also the balance that Berliad's FRW character creator uses.

Plugins

If you're having problems working with items in stores, you may want to consider Lazjen's CPS Inventory Manager. Some features in this plugin include:

• Full item listing per store tab panel
• True Item Costs that match in game amounts
• Icons shown next to items
• The ability to choose the quantity of an item (use -1 for infinity in Stores)
• Link to the property editor and previewer
• A selection of filters on the items shown: Included Base Item Types, Exclude Creature Items, Exclude Zero Quantity Items, Exclude Zero Cost Items, Cost Range Filter, Name Filter and Description Filter
• Some filter settings remembered between sessions (work in progress)
• Buy/Sell item types setup for Stores