Was grabbing my level 24 spells, and saw a vendor in the Felwithe enchanter guild (forgot the name - one of the ones in a back room) was selling Enchant: Silver-Platinum. In classic you could buy them from Neriak 3rd Gate only. I did a bit of resarch to make sure my mind isn't too faulty :P.
Source:
http://web.archive.org/web/200012051...llakhazam.com/