Today of course is Labor Day in the US, an old celebration of work. In an economic sense, work is an attempt to add value, but it does seem that some values can be more valuable than others.
Take NetherWerks' adventure Gathering Mold. A business will fail badly without the help of the adventurers. So how much is their work worth? The going rate? More? How much if the owner is desperate? When does a price become excessive if the work being done is essential?
Maybe the most profitable work adventurers could do in a medieval-themed fantasy or post-apocalyptic sci-fi setting is set up a relatively luxurious but highly complex system only they understand, involving pumping of waste say, or farming exotic plants and creatures, or simply an intricate money-lending operation - to build dependency.
Then all they need do then is threaten to stop, or point to an imagined or exaggerated threat on the horizon. What would the consumers not do to keep the good times rolling?
It is highly immoral after all, but hey, this is roleplaying, and when we act we make our own realities. Lucky that only happens in roleplaying, right, or where would we be?
We just have to hope imagining the worst doesn't cause it.
The problem of economics in games has come up many times, but the solution could be simple. We can spend time detailing an overarching system, using spreadsheets say, by applying clear rules to a given degree in advance. But we can also work from the ground up, applying those rules as we go, as a consequence of individual actions.
The characters escort a delivery of stone. The expense rises to include their work, a kind of insurance, but risk of loss falls; the building is finished sooner, new structures can be planned better in terms of cost and schedule, and interest grows in the benefits of stone over wood. Prices rise, suppliers look to enter the field; shipments increase and stone starts to become commonplace. Risk of fire falls, general health improves and population grows more steadily, with new tradesmen appearing. Razing is now more difficult; tactics of armed groups change. Waves of interactions rippling out.
Everything's fine so long as they don't get carried away, or take their eyes off the basics.
This sees a world evolve, begin to live in a sense, with the adventurers at the centre of it, which fits the approach of many games. We can start with arbitrary numbers, just as we start with arbitrary rules, but keep thinking and moving things on.
Worlds are built from the bottom up.