FormerlyHemlock
Hero
Pshhh. A castle is worth one hostage: the previous owner.
I never get why people say the prices are ridiculous. Of course they are! ECONOMICS IS CRAZYYYYYYYYYYYYYY! Money has no inherent value! Prices are only logical in perfect theoretical markets! Infinite gold results in a lack of scarcity, driving down the value of gold as a substance! The more you own, the less everything is worth to you! Where does money even come from, and who's backing it anyways?
An entertaining exercise is to design a D&D world economy in such a way that the PHB prices and assumptions actually hold and make sense. The most important thing you need is for gold to have some kind of intrinsic value beyond its value as a medium of exchange. For example, if gold is the only way to bribe dragons into sparing your life, and major trade routes are dragon-infested, then gold becomes something akin to jet fuel in our world. Now there is a good reason why someone needs to go and kill dragons and take their gold: so the economy can continue to function.