Maybe reaching out in other SW forums (example: http://www.starwarsspanishstuff.info/), otherwise resellers like ebay seem to be the only option.
Here's some pics from a forthcoming TWC073: (not certain if it's a Rental or the 80s Alquiler : La Guerra de las Galaxias)
Subtitles:
(picts of the rest of the subs are in the folder)