Pathfinder - Lineage
The base value associated with a city built in this manner is tied not to its size but rather to the number of Economy-based buildings it has. Each such building, whether it’s a shop, tavern, or brothel, increases a city’s base value. Any magic item equal to or lower than this base value in cost is available for purchase 75% of the time—this check may be made again every month (as new stock comes and goes). Any nonmagical item from the equipment chapter in the Pathfinder RPG Core Rulebook is always available if its cost is lower than the city’s base value. Cities with multiple districts add the individual base values of each district together to determine the entire city’s base value, with an upper limit of 16,000 gp per city.