Back in July I proposed to limit the availability of goods on my equipment table, which I've worked at casually these last few months. I believe I've got a system now that works, something that would guarantee that goods produced in or near the market would always be available, while things farther away became increasingly rare.
The simplicity in the system is that I make no attempt whatsoever to describe the 'supply' of the item, nor its local demand. I argue that such things do not need to be computed, if we reason that scarcity is controlled by the relative cost of the item (players will be unable, or willing to buy items even if they are available) and abundance controlled by the general nature of the system, which can be examined here. It is not generally understood by tourists of Economics that 'demand' is a product of the industrial revolution, and not a consideration in mercantalist systems ... given that the world was quite used to demand not being met and the starvation of helpless people being a commonplace thing. Of course people demanded things, but the middle class had yet to be invented and mass-production did not exist. It did not matter if more people in a town demanded shoes, for instance, since the shoemaker could not increase his output and the number of skilled shoemakers in the world were finite ... to invent new shoemakers out of thin air was not something that could be done as easily as putting up a factory and having machines built that would do the job.
I often encounter an insistence that modern production/economic rules must apply to non-industrial societies ... a thinking box which suffocates many attempts to create a fictional medieval trade economy. The simulation immediately seems vast, with endless variables - when in fact most of those variables aren't applicable.
But enough about this.
All we want is to be able to say whether or not the product is available, and how many of the item the player can buy or sell.
Towards that end, have a glance at the three images below:
(Wouldn't you know I'd screw up the graphic? The Purchasing block should read No. / Price / Unit)
The table is divided in two parts, the first being what a player would normally see as an equipment table, the second being the number of things which this luthier would pay to buy, and how much the luthier would pay. Note that there are changes in the tables, but not excessive ones ... and the bigger change is in what the luthier will buy, rather than what he has to sell. Note also that some products are always rare, and unavailable, except when you're actually in the region that produces that object. If you want violins, you'll have to visit Italy.
These are all from the same location (at present the mean location for everywhere, so a place that doesn't exist), and would represent a different moment in time. The idea is that it presents not the number of items available in the town, but the number of items the players can find in the space of one day ... or week, I haven't quite decided. Just because there might be four times as many lutes in a particular town doesn't mean the party has found those other lute shops while schlepping themselves around. And yes, generally the lute shops all tend to be on the same street (although this was not always so, though it was common), it still doesn't mean that the lutist isn't working on an order for someone else, or that someone didn't just come in and buy up all his stock five minutes ago.
The important thing is that the supply is limited ... and that if the party finds a treasure that includes fifty lutes, they may have to search through the town for quite a while to eventually unload them all (particularly if I make the time frame a week).
A side note ... the table is intentionally created so that some objects can be both for sale and for purchase - if it so happens the luthier is short on those things. Note the price will allow the luthier to make a little coin on the exchange.
Something else about this table and its importance. I plan to build my treasure tables out of the same figures (I think I can see just how to do that now) ... which means that the most likely treasure will also be items that are plentiful in the local area - and therefore, not something the local merchants will be interested in buying. Which is only natural. The local orcs will be most likely to steal barrels of ale if the local industry is a brewery, shipping barrels of ale out along the local roads. And if the party kills the orcs, and gets back the barrels - whose barrels do you think they are? You expect the local merchants to buy the barrels back?
I'm liking the system. I'm still calculating the numbers for the 1,300 goods and services involved, both sales and purchasing, which is mostly at this point a lot of formatting to make it all look pretty and easily edited later when I want to add MORE things. I can see other ways to fool with it, and additional complications I can add later, if I want to - but that's probably something I'll leave for a couple of years. This is enough of a change for now.
There are always other projects beckoning.