interwyrm said:
Every game I have played in, people assume that if they go into a big enough city, they should be able to buy anything.
First misconception. The DMG gives limits to the most expensive item that will be available. I haven't dug around it lately but I think many of the big items are not on it.
I was looking at the tables in the DMG for creating cities... the highest level wizard/sorcerer that will appear in a metropolis (by random generation) is 16. This means that you will never be able to buy 9th level scrolls or items that require a caster level of 17 or above.
It's a fallacy that everything for sale has to be made locally. Temples at major cities may have a handful of powerful items provided by the most greatest priests in case of dire emergency. Where do the powerful priests live? Well, I guess it depends on their enemies. It could be a demiplane that is reached via Gate.
Same goes for archmages and super-druids. They tend to keep an abnormally low profile to minimize the odds of an enemy incinerating their allies. Mobility is the greatest defense. (Think Gandalf wandering around doing fireworks shows)
Also... why would anyone ever build a ring of three wishes or a tome of ability score, and not immediately use it afterwards.
Legacy ("I'm an old mage unlikely to gain enough XP to get the life extending Epic feat..."), contingencies ("Crap, I can't cast anymore Wishes since it would drop me a level!"), and special events ("Becoming a lich will give me much power but my death will disrupt the magicks that augment my body...").
How do item crafters get the experience to craft their goods? Are they all adventurers?
A classic question. "How do NPCs earn XP? And how fast?" NPCs earn XP same way everyone else does; overcoming challenges. They tend to be more social or political than physical. However 3.x isn't about killing, it's about overcoming adversity. Beating a local politician at his own game is a challenge worthy of XP.
How fast? Up to you. I generally give out ~4 levels/age category so that venerable NPCs will have double-digit levels. Some give out more, some less. My rule of thumb is that crafters can spend level x 10 XP/year on magic items without impinging on their advancement. It's not a whole lot (10th level caster = 100xp/year = 2500gp items) but does account for many things.
You may also want to look at the Eberron Artificer. I'm told it has interesting rules for crafters but I haven't examined it yet.