Yes, that 900gp is all wealth, not just liquid assets.
And the 5sp thing is preposterous, as 99% of the population will have a lower cap of whatever they can make with their +3 profession check (or a fixed income around that value for employed workers). This makes gold actually a fairly fluid thing. There's a LOT of it sloshing about in the economy.
As far as your metropolis, you'll also need to figure that the size of the city will both limit the effectiveness of public works projects, and assist in the bleeding off of that wealth (the adventurers have to be getting it from somewhere). Your city is going to be at least three square miles in size (larger, if you give the middle class more modern land allowances, and the noblemen urban estates). That's a lot of area for a city to police, as well as the farmland that's feeding this monster.
I agree with the above posters; either this society will quickly become a beacon of standard of living for people through magic, or it'll be a crater. The amount of money flowing around and the cost of mass public works through magic are too high and too low, respectively. The only thing that could stop that, I feel, is if the city existed in a permanent state of war. Either against intelligent outsiders, or organized crime, or hordes of beasts. SOMETHING has to be bleeding off enough wealth and resources that the society never quite manages to sock enough away to finish that water system, or the everburning flame streetlamps, or the endless food delivery services.
That is, if you want to maintain the classical D&D feel.
And the 5sp thing is preposterous, as 99% of the population will have a lower cap of whatever they can make with their +3 profession check (or a fixed income around that value for employed workers). This makes gold actually a fairly fluid thing. There's a LOT of it sloshing about in the economy.
As far as your metropolis, you'll also need to figure that the size of the city will both limit the effectiveness of public works projects, and assist in the bleeding off of that wealth (the adventurers have to be getting it from somewhere). Your city is going to be at least three square miles in size (larger, if you give the middle class more modern land allowances, and the noblemen urban estates). That's a lot of area for a city to police, as well as the farmland that's feeding this monster.
I agree with the above posters; either this society will quickly become a beacon of standard of living for people through magic, or it'll be a crater. The amount of money flowing around and the cost of mass public works through magic are too high and too low, respectively. The only thing that could stop that, I feel, is if the city existed in a permanent state of war. Either against intelligent outsiders, or organized crime, or hordes of beasts. SOMETHING has to be bleeding off enough wealth and resources that the society never quite manages to sock enough away to finish that water system, or the everburning flame streetlamps, or the endless food delivery services.
That is, if you want to maintain the classical D&D feel.