In the A&EG there's the hammer of the magesmith, which reduces the base cost of any weapon by 5%. Note that shields count as weapons since you can bash with them.
The Shield Dwarf Warder feat from Races of Faerun reduces the cost of magic arms and armor by a further 5%.
In Hyperconscious (written by Bruce Cordell, author of the XPH and the good parts of CPsi) there's the Craft Dreamgift feat, which allows you to make dreamstained items. If you don't mind taking Con damage every day and suffering nightmares every night, you can knock down the price of an item by 3/4, though it also knocks the caster level of the item down by half, making dispels a potential problem.
Words of Creation (from the BoED) boosts the caster level of items by +1 for free, which can be a huge reduction in cost for some high level items. See the psychoactive skin of proteus, for example.