To paraphrase America’s beefiest statesman, if it’s got hit points you can kill it. In the same way, if it’s got a price tag you can buy it. You’ll often hear how it’s a bad idea to stat out gods; how players will inevitably find a way to overthrow the cosmos if you do. You get similar results when you take a pricing gun to the game world. This isn’t much of a problem if you run your campaign like a game. By buying up the world, players are just allocating their resources in the most efficient way possible. No harm no foul. Everything is working as intended. If you’re going for a more narrative approach, however, then you run into problems.

Magic items, miracles, and easily accessible spellcasters willing to sell their services are not simply property to be bought and sold. (Well they are, but bear with me.) From the narrativist perspective, they are also plot devices. They are quest objectives and story rewards that can and should come about through narrative. If you lay them out in the rule book like some kind of Sears Catalog, players begin to think those things are always available. “We’re in a metropolis! What do you mean we can’t get an archmage to make us a water park deminplane!?” 

Here’s my point. We’ve talked a couple of times about how items ought to feel special. Wishes, miracles, and magical boons should as well. That’s not to say you can’t ever buy them with your hard-earned dollars gold, but for the good of your poor beleaguered GM, at least try and pretend like it’s a special occasion.