i honestly wouldnt pay over 50% for a used lens... but thats just me.
How many shots has it taken? What kind of weathering/terrain has it seen, how was it handled etc...
im stickin with 45 btc tbh.
Its in like new condition except for the one quirk I noted in the OP. It belonged to a relative of mine, he's an older gentleman, casual amateur shooter. I seriously doubt he took 1000 shots with it, certainly not in bad weather/terrain.
For a cheap used lens, I'd take a 50% cut. But this is not a cheap lens, its built very very well, and performs & handles as one would expect from a $600 lens.
Gonna pass this off to a friend of mine with a Canon DSLR to take some sample shots. I will also update the shots of the lens itself, as they're not good enough.