http://feeds.feedburner.com/~r/mudreading/~3/263582409/easy-supply-

A realistic economy is a goal of many MUDs. Many of the benefits of a realistic economy can be created with very little work.

Here is a simple supply and demand system. Every time a player buys an item, increase its cost. Every time a player sells an item, decrease its cost.

Voila. Supply and demand. The system works well to make high-demand items expensive and extremely common items cheap. There are just a few tweaks that would keep things working.

Tweak the settings for how much the cost is effected by each purchase or sale. You can’t assign the “right” values deterministically. It depends on your playerbase’s size and behavior, and will change over time.

Consider having the prices normalize gradually over time. That way a surge of unusual activity will be offset sooner, and items that are bought but not sold (such as consumables) will not simply increase in price forever.

Consider a minimum and maximum price. EG, do not allow an item’s cost to change to 50% less or more than its original cost. This is a good approximation of other factors not considered in the system and helps catch flukes before they cause a problem.

To expand on the system a little, keep a multiplier for object types and materials, if you have them. Start at 1. Each time a player buys or sells an item, increase or decrease the multiplier (by a small fraction). Have the multiplier effect all objects of that type or material. Now, if silver longswords are in demand, the price of silver broadswords will increase as well.

To expand on the system even more, keep these set of values separate for each city, region, or whatever granularity is appropriate for your game. Then travelling to a region where an item is more rare will yield a better payoff.