Would you pay more than 25% of MSRP for a used cartridge?

lemme guess. you low-balled a seller at 25% of retail for a scarce and hard to get cartridge that rarely shows up new let alone used. you were then turned down multiple times by many sellers. your rationale is that all sellers are liars and not to be trusted re claimed hours of use, etc. got it. 

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:

1. A straight cantilever that is not askew, and if possible an "on record" pic to show it’s not riding too low.
2. 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. 

I just bought a used cart here. Ortofon Cadenza Bronze. Great deal. About 40% off list give or take, these carts never go on sale. It’s a good way to try different sounds. As with anything mechanical, buy the seller, not the item. In this case, the cart was a dealer’s personal cart. Listening to it right now. Excellent!

i have purchased many used cartridges

it is all about doing homework on the seller, knowing when to back off/move on... and buying the potentially risky ones in a way that allows proper recourse in the worst case scenario

“Caveat emptor” is good advice for probably more than 2000 years. “Trust but verify” also is a good motto. Get a pre-purchase inspection done by an expert. If someone like Peter Ledermann or our Needlestein confirms low use and perfect structure. I’d be all in. Such a specimen is worth much more than 25% of MSRP, to me, if I want it. If a seller won’t agree to a PPI, done at my expense, I’m not a buyer at any price.