Indeed, that\'s a very simple economy that works well in MMORPGs, Gronomist. Personally, I think player-ran econmies are best, but that requires a large player base, which we don\'t have at the moment.
I\'ve always thought of econmies are purely social creations, I\'m not sure if hard coding an economy into the game would be the best idea...
However, here\'s an idea that expands on Gronomist\'s concept. Suppose there were several broad types of items (eg. Consumables, Weapons, Metal...), and many narrower sub-types (eg. Fruit, Swords, Steel). Now, assume that there is a table of demand for each Type and each Type/Subtype (probably should be implemented as a map, to allow for new types to be added easily). NPCs would price items for buying and selling based on the demand values in the table, buying would increase demand for the particular Type and Subtype, while selling would decrease demand. If demand for a particular item fell below a certain amount, that item would be considered worthless and most NPCs would no longer buy it. It could be implemented by region, making for some items that are more exotic in certain areas of Yliakum, which would naturally facilitate trade.
This would create for a more dynamic economy than in most MMORPGs and MUDs. It would require players to change and adapt to rapidly changing conditions around them, much like in the real world.