A classic case of...
Here is some BREAKING NEWS: Old Horns And Mouthpieces Are Going Up In Value. I know this might shock some people, but yes, things that are not made anymore will keep getting more expensive.
This is a good, classic case of inflation and supply and demand. As mentioned earlier in this thread, the dollar is getting weaker. Add in items that are becoming even more rare, and you have the prices of those items increasing much faster than normal market conditions.
In the case of this Meyer mouthpiece, as Landrusax has said, the value of this piece would probably be just right. I agree with him, however, just because the price of the Meyer is justified does not necessarily mean that it is a justified purchase of a mouthpiece. In short, if you are looking for a mouthpiece with the ultimate sound, the price of this rare Meyer will not guarantee your personal satisfaction. I can personally attest to this claim, for I have tried and bought many different mouthpieces that also carried hefty price tags. Despite that tedious charge, I surprisingly found my ideal sound with a $15 Rico Royal mouthpiece.
In terms of investment, this Meyer piece may prove a bit more useful, but given the fact that there are so many investing programs that would achieve the Meyer's appreciation rate in a significantly shorter time frame, I think it's best to place our money somewhere else.