There is suppose to be a gentleman on the forum by the name of Erick (I believe - if I remember correctly), that has years of experience as a lens technician whose abilities are legendary with Pentax lenses. I have read that he has successfully repaired lenses with fungus, dust, oily blades, and many other problems. His contact information is somewhere here on the Forums. Maybe, you could strike a deal, where by the seller would send it in, and if it is repairable in Erick's opinion - you pay for the lens and repair (possibly with a repair adjustment), and if not we all know what 85mm lens to not buy....
I also, recall that there was also another person that repaired Pentax lenses too. It would be nice to have this information on a sticky here on the Lens Forum. I know it may be looked at as an advertisement, but......
I think I found it.
I might even be inclined to email him the image here on the thread and ask if he thinks that it might be repairable, and then decide what to do...
Fortunately, I have never had to have a lens repaired, so this is just from what I have read.....