There used to be a great place right across from Meredith College, but they closed a couple of years ago (big help, I know
).
It may be a long shot, but call one of the local theatres like Raleigh Little Theatre and ask for the costume designer (at RLT, her name is Vicki). They would know of places that rent and, just MIGHT rent you something out of their own stock if the cause was right. Ditto for theatre departments at the local colleges such as University Theatre at NC State, or Meredith or Peace. At the very least they might know where to point you.