Meerschaum Lined, Broken. Need a replacement

http://www.ebay.com/itm/5-NEW-MEERSCHAUM-INSERTS-CONICAL-FROM-GERMAN-FACTORY-1950-60s-EASY-TO-WORK-OUT-/381069791245?pt=LH_DefaultDomain_0&hash=item58b987900d
I have ordered stems from this guy before. I'm in the U.S. Also on pipesreborn blog the guy there will patch them with plaster of paris and has good luck with that.
The walls look decent sized so you could just pull the insert out and build a cake.

Pulling the insert may prove to be a little harder than expected depending on how the insert was originally put in. Most makes of briar pipes with inserts drill a hole In the briar that matches the profile of the insert exactly. The insert is then fitted as a solid piece into the hole and put in place with an adhesive. One the adhesive has cured, the bowl is machined out of the meerschaum and then the draught hole is drilled. Most people think the bowl in the briar is machined first and then an insert is put in, but as you see that is not the case.
Fitting a new insert is going to be a challenge. Not only do you have to get all of the old one out without damage to the briar, you are going to have to match it perfectly to the profile of the hole originally drilled in the briar. Not impossible, but definitely a challenge. Then, you are going to have to carve/machine the bowl and drill the air draught hole.
My recommendation is to clean up the bowl and patch it. Check out the pipes reborn blog as Snagstangle suggested. If you need any help or recommendations, let me know.

I doubt you will find a liner anywhere. It looks like it's the bottom section. Yes? I have read of fellows using grout as a patch. Stick a pipe cleaner through the draft hole and fill around it. Grout might be heavy though. I'd think you could just use pipe mud to the same effect. Same exact method. It works on the bottom of a regular briar bowl. Should be good here too.

Sounds about right. I had often pondered how they did the meerschaum inserts and that now makes perfect sense.

That article is about myths that people believed at one time but were not, or were probably not true.
Meerschaum is NOT plaster of paris. Although pressed meerschaum, which I think is what most bowl liners are made from, probably does share similar characteristics with PoP. But it isn't the same. And moisture would probably degrade PoP much faster than it does pressed meerschaum.
That doesn't look like an expensive pipe. Do a simple patch.