The Wish Economy (I didn't make this up, google it) was an interesting phenomenon in 3.5. Basically, by the book, you could chain bind efreet at 11 level (earlier with a scroll), and have them wish you up tons and tons of cash, but they couldn't wish up magic items over 15k gp. This resulted in many GMs seeing their game setting as one in which there are two seperate economies working, the normal and elite.
In the normal economy, everything functioned as per DMG, except there were never any major magic items to buy. Major magic items belonged in the Elite economy, where they basically were only available as rewards for quests, for equivalent trades, or for some sort of unobtainium, like souls, ransom for powerful NPCs, etc.
At first glance, the Wish Economy was removed from Pathfinder RPG. While chain binding Efreet is still RAW-legal, the wish spell has been changed, you can no longer reliably wish for money or magic items. (you can still totally get +5 inherent bonus to every stat, raise an efreet army, etc, but these aren't the topic here, and are mostly ok as the Efreet take it personally and can plane shift to here to take revenge after the spell wears off. Also, the +5 to all abilities helps fighting classes disproportionately, and that is good at 9-12th level, where it happens.)
However, it seems like the default setting has been designed with the Wish Economy pretty much assumed. According to the section on Buying Magic Items (page 460-461), items that cost more than 16,000gp are just not really available (except for a tiny number of randomly generated items per city). Given that it takes a powerful spellcaster over 2 weeks to make one, and the only others who will have them are high level NPCs or monsters with treasure, it's basically the same effect. Magic items up to 16k gold are purchasable with $$, Magic items worth more than that are only gotten as loot, rewards, or crafted by PCs.
My suggestion for GMs is to make the random major magic items available in each city barter only; you can only get them by trading other major magic items. This increases the appeal and makes every appropriate major magic item something worth going on a quest for.
Which is the way it should be, anyway.