I had a dealer tell me that two lenses I was selling had to have a lesser price tag due to fungus. I was pretty surprised as they weren't old at all. I was told that depending on storage conditions etc etc this wasn't uncommon. As these were on a commission sale I thought it wasn't in his interests to sell for lower so believed him.
As an aside, are there not "anti-fungal" lens cases? I'm sure I've seen some advertised on sites?
"Photography has not changed since its origin except in its technical aspects, which for me are not important. "