I read in an answer that you can provide the XP cost of an item that the party Wizard creates for you.
Unfortunately no details are given, and the link is dead.
How can I cover the Wizard's XP spending?
That Web article is part 1 of the Player's Handbook II Web enhancement titled "Magic Items: Transferring XP Costs" that's now available here. It discusses a variety of ways creatures can share among themselves XP costs incurred from crafting magic items.
For example, there's the 1st-level spell transference that any Player's Handbook full caster can learn; the talisman of transference (200 gp; 0.5 lbs.), a magic item that allows transferring XP; and the Ritual Transference feat, a new feat that allows transferring XP that a character gains automatically and for free after creating 5 talismans of transference.