Re-tipped Cartridges?

I have noticed that there are a fair number of what I consider to be fairly well regarded cartridges (I.e. Koetsu, Van Den Hul, Etc..) that have been re-tipped and then almost immediately gone up for sale, either here on Audiogon or on Ebay. These cartridges typically have very few hours on them (usually less than 10 hours or so), and are very reasonably priced, usually less than a used non-retipped version of the same cartridge.

I have only just gotten back into vinyl, and therefore wonder:

Are these re-tipped cartridges no longer as good as they were?

Have they changed their sound, so that while they may not be worse, they are just different?

Or have the owners just moved on to either a replacement or to their backup cartridge, and grew to like them better than the re-tipped cartridge?

At some point I am going to want to upgrade my cartridge (currently a Koetsu Black) and wonder if I am getting a bargin by getting a re-tipped cartridge or getting a second rate cartridge.

I particularly would like to hear from those who have had cartridges retipped, and have heard the sound both before as well as after the re-tipping.

Thanks for your input guys.
It depends a lot on the brand. I can't speak for Koetsu, but some companies do thorough and excellent rebuilds, and others literally re-tip. The good rebuilds will include a new cantilever, stylus and coils, and are not cheap. Re-tips are sometimes nothing more than a new stylus glued on to the old cantilever. Good rebuilds are definitely worth it. I have had my Linn Arkiv factory-rebuilt twice since 1995 and it sounds as good as new. In fact, they have upgraded the cantilever along the way.
Your best bet is to have the cartridge re-tipped or rebuilt(which is more commonly done) by the original manufacturer. This is especially true of the Koestu cartridges. If Koetsu is rebuilt by somebody else, it is no longer a Koetsu. I have heard experience after experience from people who have done this, and were disappointed.

If you have a VDH cartridge, then send it to VDH for a rebuild. If you have a Koetsu, then send it to Koetsu. If you do the opposite, you will have a VDH/Koetsu, which is not the same thing. It will not sound the same, and it will not be the same. Most people that want Koetu, want to keep the Koetsu sound, not have a VDH sound in a Koetsu body.

Just my 2 cents.
From my re-tipping VDH black beauty experience, they do not sound the same after re-tip due to long break-in required. The original sound is more emotional, softer highs than the re-tip. However, the re-tip sounds better with Jazz music. The sound become punchy and more exciting. Just can't enjoy the string instrument during the break-in period. The cartridge settles down after 300 hour break-in. The VDH cartridge typically last about 2000 hours ( according to manufacture specs.) but I would say the best enjoyment probably between 300 to 1000 hours.
Many folks how owns VDH probably didn't have the patience to wait it out and therefore you see them on audiogon.
I hope this helps you determine if VDH is for you or not.
What S23chang says about break-in is true of any new or newly re-tipped cartridge. So, I wouldn't let breaking in disuade you from buying a properly retipped one.

Definitely follow Twl's advice....