Trading mechanics and deciding product/building costs.

Hello everyone,

I am thinking about trading game mechanics and trying to figure out how to make some calculations or decisions in a trading game. I am talking about costs like trading goods, price differences according to cities or building cost of a farm which will give you profit of 1,000$ in a month etc.

Thing in my mind is not a simulation kind of game which depends on multiple conditions and variables like in "Capitalism II" but something much more simple like trades in "Sid Meier's Pirates". So i don't think i will need most accurate precision or complex calculations which depends on thousand variables. However i have to keep the balance of the game.

As I am not an economist and not very good at math, i don't know if there are equations for this kind of problems. So i think may be i can decide them myself without an equation. So those prices & costs (kind) of will depends on my instinct if you get what i mean.

What do you guys think about it, how can i keep the balance and avoid of unrealistic prices?

Does anyone has an idea?

As a general rule, any action ought to come with about 40% markup. So you might buy good 1 at $100 and then sell it for $140. And then the prices of those upgrades enable more volume. If one takes over the role of producer instead of trader, they get that 40% markup twice, so they produce it at a cost of $71 and sell it at $140. This is just a rough idea that mimics real world values. Costs of upgrades and upkeep ought to be scaled based on the difficulty.