There is also the option of 2 spirits, 2 bronze or 1 spirit 3 bronze for a bit of extra XP. Using the Hashims from BSII that gives ~1.5K or ~1K xp, depending on whether you use 2 platinum spirits or 1.
Will still be expensive, but depending on how easy it is for you to obtain spirits and bronzes, it could be an alternative to the elusive platinum armors.