New or used cartridge

If the cartridge was produced in the last two years then it probably
has under 200 hours. Most cartridges are good for 1000 hours.
I have had exceptionally good experiences buying used cartridges
on Audiogon. Most of them were cartridges that people did not
like because they failed to break them in. You will usually do much better buying from an individual than a dealer. Finally if you find you need to replace the stylus than Soundsmith can do it for a reasonable price and usually a better stylus. 

The MicroRidge and similar advanced LineContact styli must be replaced after 2000 hrs, the Conical and Elliptical stily must be replaced every 200-500hrs. 

Handyman, you mention an Urushi.

If you are considering rising in the Koetsu line, note that Koetsu likes to service their own cartridges by completely rebuilding them. It is said that they will not touch a cartridge which has been serviced by another.

Therefore, your options are limited. You could get someone (like Soundsmith) to inspect the cartridge, but not service it. Then, if necessary, send it to Koetsu for rebuilding at great cost. The result of this would be essentially a new Koetsu with Koetsu sound. Unless Koetsu refused to rebuild it because of tampering by the former owner.

Alternatively, you could get someone like Soundsmith to service it at lower cost. But you might not get Koetsu sound or Koetsu longevity.

I have the KRSP with diamond cantilever and like it a lot. Rebuild price will be very high - hope I can afford it come the day. But after 700 hours the stylus still looks good.

Terry9:  Thanks for the info, but there's nothing wrong with my Urushi Black. Just thought I would move up.                                          Steve

@terry9 
Consider having your Koetsu rebuilt through a Japanese or Asian deputy service. E.g. EIFL (Japan) advertises this for low-2000s on stone platinum model. Otherwise, the USA distributor & dealer will each take a hefty cut, and do nothing to expedite the process. Also, the rebuild cost does not rise for the premium stones, so the long-term cost on say a Coralstone can start to look pretty reasonable. 

I've also heard that Koetsu will not touch a cartridge that's been worked on by any 3rd party. Not sure if that still holds, but it certainly keeps me away from any 3rd part work. Over the years I've seen an awful lot of Koetsu with SoundSmith ruby cantilevers "less than 10 hours", etc, for sale.