I've bought a few used cartridges here with good results. That is reason enough for me to consider buying used again. My criteria is under 100 hours, shooting for 75 hours or less. It's pretty hard to lie about a cart with that little use. They do come around every so often. When I see a cart advertised at 200 hours or more I will always double that to get a realistic number.
If you use this method, along with Ekobesky's comments above, I think you'll be OK.
If you use this method, along with Ekobesky's comments above, I think you'll be OK.