Normally, such bags could only be bought from traveling merchants who traded across races, but the prices were astronomical. Fortunately, thanks to Zion's successful diplomatic efforts and trade agreements with the dwarves, he was able to purchase them at a significantly reduced price, though even then, a single magic bag still cost as much as a year's worth of grain for a typical pack.
Fortunately, thanks to Zion's foresight in establishing trade with the elves and dwarves, and profiting immensely from the items he acquired through his trade routes, he had amassed a significant fortune. In fact, his pack had become one of the wealthiest in the entire werewolf kingdom, despite being politically isolated by the Alpha King.