I have purchased 2 used cartridges here on Audiogon and both experiences were good. There is no question that buying something like this entails taking some risk. I recommend sending a note and asking some questions along with requesting some pictures particularly of the cantilever. Getting a reply from a reasonable person is very reassuring, at least to me.
As an aside, I own an old Wild-Heerbrugg microscope set up specifically to look at phono stylii under high magnification. It is possible to assess wear/estimate hours of use with it. I know not everyone can do that, but if you have a dealer or know someone with a good microscope, a quick look is worth a thousand words. I wish I could figure out a way to offer to do that as a free service for this community.
As an aside, I own an old Wild-Heerbrugg microscope set up specifically to look at phono stylii under high magnification. It is possible to assess wear/estimate hours of use with it. I know not everyone can do that, but if you have a dealer or know someone with a good microscope, a quick look is worth a thousand words. I wish I could figure out a way to offer to do that as a free service for this community.