Working in Retail

My players have decided they want to become opium dealers.  They are in a fairly small city (Remballo, 1,344 families) that I've classified as a Class III market because it is home to a large banking family.  It's nearby a large city (Manas, 5,684 families, Class II market) that is a major opium trading hub.  They want to buy opium in Manas, transport it to Remballo and sell it by the dose to people there.  Opium is fully legal in this realm, but there is still a lot of violence surrounding it.

I've calculated demand modifiers for both cities.  Manas is at +1, and Remballo is at +2.5. Just to get a sense of the numbers, I said that a load counts as 100 doses. I set the base price at 200 gp per load.  I calculated the market price of one load to be 170 gp in Manas and 250 gp in Remballo.

The problem I'm having is how to go from those numbers to some sort of demand curve for Remballo that specifies how many doses they can sell vs. what they charge per dose.  Again, just to get a sense of the numbers, I estimated that since they will have a monopoly they could sell 400 doses (4 loads) per month at a price of 5 gp per dose (100% retail markup).  Their gross profit would be 2000 gp.  Their net profit would be 1320 minus tolls (~25 gp), duties (~100 gp), transport costs, rent on their opium dens etc.  I haven't calculated their rent yet, but I'm estimating that they could clear 800 gp per month, which seems like a nice, non-campaign breaking amount that compensates them for the risk involved.

Does anyone have any experience doing these sort of calculations?  I would appreciate any holes you could poke in the reasoning above.

The mercantilism rules assume that the adventurer is doing pure arbitage; you don't buy eggs to sell in your breakfast nook, you buy eggs to sell to the breakfast nook guy. Being a small business owner is not well supported. 


That said, what you've got there doesn't look broken. I wouldn't worry about a demand curve; optimizing the price/supply ratio, is, I think, a level of simulation D&D doesn't call for.

The closest ACKS currently comes to rules for small business is that for 1,000gp you can attract 1d10 peasant families who will produce around 12gp per month, yielding an average profit of (12 - 2.4  tax - 1.2 tithe - 2 garrison - 1.67 festivals) 4.73gp. Assuming an average of 5.5 families that is 26gp per month or 312gp per year, which reflects a typical rate of profit for ACKS of about 30% annually.

But annual profit could be as low as (1 x 4.73 x 12) 56.76gp per year, for a rate of profit of 5.5% or one-sixth the expected rate of profit. It could be as high as (10 x 4.73 x 12)  567gp per year, for a rate of profit of 56.7% per year, or one and a half times the typical rate of profit.

To apply this to your situation, imagine that your 800gp is profit is the result of a roll of 5.5 on 1d10. 800/5.5 is 145gp. So let profit equal 145gp x 1d10 per month. 

You could if you'd like say that on a roll of 10 the characters have an extra-profitable month, gaining an additional 1d10x145gp, and that on a roll of 1 they suffer catastrophic losses, losing 1d10x145gp (less the 145gp of the 1 result, to keep the math even).

I suspect you will probably want something less abstract for your game, but I hope that at least helps with a benchmark against other activity they could pursue.

That's a great idea.  I think I will incorporate some sort of fluctuating income.  I already planned to have the cost in Manas fluctuate according to political events (which the players may have some hand in).  It makes sense that the demand in Remballo would fluctuate as well.