What the cinnamon toast fuck is the economy in this tower? Is one coin cheap or exorbitantly expensive?
Yes
Edit: they mentioned how much a tower coin was worth in Won way back, but I just think of it as a coin is ~10 usd, so $5 for water is a bit much.
Continuing on, a grilled fish is $10, and I had a diatribe about it but earlier it was shown that he tried to buy a fish for 1 coin at the town, so I'm assuming a coin for a higher-end fish is average, thus they're selling cheap fish at the price of expensive fish.
Finally, by this metric, a 500 coin debt is worth $5000, not too much when your father is rich, but when you're broke, thrown out of your house, and the Black Dragon himself is right there, $5000 is a lot of debt.
It also implies that he's "paying" them 10¢ a day, but considering they receive room and board along with the general scamminess of the situation I can buy it.