Pretty simple: PCs do not create magic items, and magic items are rare in general, though usually powerful (with the exception of scrolls and potions). If a player wanted to create a magic item I would drop the xp requirement, but demand some exotic component or process or text, therefore getting a few adventures out of the creation.
I am also a fan of magic items that grow with the wielder, usually not by getting upgraded by a mage though, but by "making them whole again", or "fullfilling the destiny of the weapon" or other quest-like "processes" inserted at fitting places in the campaign.
The barbarian's spear he got in a battle turned out to be a stolen spear a desert tribe had prepared to kill an ancient foe of the tribe, a giant monster, so it kind of fell to the barbarian to do the deed, after a spiritual test of his courage and morals, and the spear was completed for the quest.
The priestess/duellist has an ancient sword which is a part of a legendary weapon used to defeat an evil wizard in the past, trapping him in between undeath and life, but getting shattered all over the planet in the process. Now the party and the minions of the evil wizard are trying to gather the parts so that the wizard can be killed for good/resurected/transform in an undead.
The knight got his blade as a gift from his weaponmaster upon completing his studies, and the blade bonded with him, growing with him (he can use meditate and add new powers to the blade with each new level in his blademaster PrC.)