I'll talk to my DM... I might be able to sell him on the idea of a headband of intellect +4 of persuasion, as my math tells me such an item would cost about 23,000 gp. And since the rules for it are in the DMG, rather than the MiC, it might be an easier pitch. Now I just have to wait for him to get online... and figure out how I'm going to scrape together the cash for this, if he approves.
EDIT: And if that fails, I'll have to go for the Vest of Resistance, as it costs the same amount and I should be able to wear one. Thanks to those who pointed out that armor and vests are clearly compatible. That would actually be much, much easier for me in the long run... and probably somewhat less expensive.