I guess as audiophiles, we’re all gonna be OCD about SOME things - but hopefully not all things. I’ve been pretty relaxed about buying high-end used cartridges. If the seller has good feedback here, I’ll trust them - especially if they look like a hobbyist who knows what they’re doing. It’s generally worked out pretty well for me. You want to see pics that show at least two things:
- A straight cantilever that is not askew, and if possible an "on record" pic to show it’s not riding too low.
- That the previous owner(s) have practiced good cleaning hygiene. Particle "beards", a blackened stylus, or crust atop the cantilever are bad signs.
You could also be paranoid about L/R channel balance, but the only cartridge I’ve encountered yet with an imbalance of >= 1dB was 30 years old.
The last cartridge I bought used was an Ortofon A90 from here - and I forget the actual price but I guess ~40% of MSRP? It's a real gem; if anything the seller undersold it.