I looked at the local prices in Singapore, and most of the going prices for used gear are way, way cheaper than in the US. Canon 70-200 F2.8 Mk II averages around $1600-$1700. A 135mm F2 goes for around $650.
Humidity is a big issue in Singapore (average humidity is 84% year round), and if lenses that aren't stored in a controlled humidity environment (a drybox) it can develop fungus problems over time.
I can inspect the lens to see if it has fungus, but what I can't tell is if it's been ever stored in a dry box other than taking the seller at his word.
So if there's no fungus now and I take it back to a mild weather climate, does the risk of fungus go away, or is it possible that there are spores that I can't see?