The amount they recieved I'd estimate around... oh... 2,000 gold. Maybe a little more. Definitely a chunk out of any city treasury. 2 gold is enough to build a small cottage. It can also purchase 3 grown cows (so 1 gold for a single young cow was overpaying).
5 Gold can purchase a building and start a business on it's own...
So, handing over 20 gold on the spot isn't necessarily an easy thing to do, even for someone who's as rich as they are.

Originally, this world was supposed to be without money, and everyone purchased what they needed with work so noone was rich, and noone was poor... noone was homeless. However, it's extremely difficult to pull off in a "primitive" setting, such as post apocalyptic medieval times... Futuristic economies are more able to live without needing money and still have a story, but money is an important aspect of this atmosphere without being too Utopianistic.

Anyways, I'm writing the next one now. I'm glad you're enjoying the story so far. ^^