When it comes to selling knowledge to aliens, to be clear, Financial Literacy Layer 2 is not going to get you there. If the answer across every plausible premise was trivial and similar, that trope wouldn't be such a staple of dath ilani economic fiction.
Thankfully, Golarion is not nearly weird enough for Cheliax to be composed of aliens in the relevant sense; the Chelish have money and will tell you how many unskilled-labor-hours it corresponds to. The most you have to worry about is that somebody gave them a dishonesty card - which does mean you have to do your own calculations about what's fair, and not just ask them.
When you are not dealing with alien aliens, when setting prices with those aliens is not the point of the story, a normal dath ilani would consider the solution obvious. There comes a saturation point beyond which individuals cannot realistically use any more money to become happier themselves, for usual reasons of just-noticeable-differences being a mostly-constant fraction of how much you already have, which implies utility roughly logarithmic in wealth. If the aliens offer to pay you that much, asking them to cough up more would mean that a number of poorer aliens would all have to give up chunks of utility that loom larger for them, so that you could get much smaller amounts of utility; and even if that's fair, it isn't Good. If the aliens offer an ultimatum for less, turn them down with very high probability; they're trying to give you far less than you're worth. Would Civilization offer less than a billion labor-hours to an alien bearing knowledge of how to eliminate whole swathes of diseases hitting large sections of the population? (No.)
Of course, in a normal dath ilani economic-fiction isekai story, the entire world you end up in is not insane in every part; there may be one insane point of departure with some insane consequences lawfully extrapolated, but the author is not going to throw an entire insane world at you; it wouldn't be credible.
A normal dath ilani, thrown into another world, does not come in expecting to need enough money to make lots and lots of important investments that the natives haven't made because the natives are insane. They're expecting to find an alien efficiency of no simple ways to make everyone collectively much wealthier, not the howling absence of that efficiency.
Keltham wasn't expecting Golarion either.
He did, however, catch on in short order to what he currently thinks is the magnitude of the problem.