Bastions is the money sink. Gain treasure. Own and operate a cool place.
I am against buying-and-selling magic items, because it becomes too much like nonmagical technology. Every magic item is like a person, that a character needs to attune to. But I favor players making and modifying their own magic items.
The larger the population the more likely to have more very high level characters. These characters would make or acquire powerful magic items. Even so, outliers, uniquely powerful characters tend to show up from anywhere.