Hi Par,
+1 on that. Many custom knives only get to be valuable once the makers stop making them. If the fit and finish is good, then it's probably worth hanging on to them.
Actually you get about an 18 month bounce after a maker stops making knives. After that the knives prices start to come down in the after market. The reason is those who follow this maker buy up (as quickly as they can) this makers work. Those collectors who didn't know the maker before hand, generally will have little or no interest.
Case in point: Jimmy Lile. Jimmy passed away in 1991. Sales continued of his knives (most with the dot over the "i" for about 8 years and then the company went out of business. Many people were not aware of what the "i" signified. So while the sale of those knives went flat, those Lile's without the dot over the i or even better "
Handmade By James B. Lile took off for two years. Then things settled down again. Next came a book about Jimmy a couple of years ago. The Lile market heated up again and now it is flat again. There are people with literally hundreds of Lile knives still trying to get those prices from the "old days." This is of course their prerogative to sell the knives for whatever they like.
Often times what happens is that the collector gets in late and buys the knife at top dollar in the aftermarket. Consequently, they now have a knife that they will probably not get their money out of. Fortunately for most collectors they don't care what they paid for the knife because they buy what they like.
On the other side of the coin, most knives from popular makers increase in value while the maker is still making knives. The reason, because the maker being sought after creates new collectors for that makers work. In doing so, those who bought early now have a new group of collectors they can sell to while the collector is waiting for their knife directly from the maker.
A maker who is no longer making knives is no longer expanding their collector market. So while there is some credence to "getting one because no more will be made". The truth is, give it a couple of years and you will probably be able to pick up a knife from that maker at a much better price than you would pay soon after they stop. The reason is once the excitement stops, collectors/dealers will want to move the knives they bought and will be willing to sell them for less than "top aftermarket prices".
Also, unless the maker is deceased....there is always the chance they can start making knives again. Generally the aftermarket does not consider this a positive thing!