I really like an item of mage armor at will. (For example, a Mage Armor Amulet.) That way, it lasts 1 hour per use, and you can pass the buff around to your whole team! It even ups your ghost AC!
If you're nonevil and you can use that Book of Exalted Deeds, then luminous armor and greater luminous armor provide uber AC boosts, even moreso with Paragnostic Apostle (Complete Champion 94) and Abjurant Champion (Complete Mage 50).
If your GM allows it, get an item of continous shield for 4000G. (It's fairly cheap and that price is by the formulas!)
Though not strictly AC, getting an auto-miss chance against you effectively boosts your AC. Blur, displacement, mirror image (normal and greater), and concealing amorpha (normal and greater) help.
Dungeon Master's Guide II has item templates for armor and shields. A feycraft githcraft mithril chain shirt has no ACP, no ASF, and weighs only 11.75 lb! Just assume a fey mind controlled a gith and forced him to make said shirt.
Oriental Adventures has the dastana and chahar-aina, which are separate items you can use to boost your AC, and these items explicitly stack with certain types of armor (like leather and chain shirts). Just get masterwork dastana and chahar-aina and you have no ACP. (Go mithril for no ASF, either.) Arms and Equipment Guide also has dastana, but the stats are identical.