The following is an opinion of mine, and only mine.
Often you will see an item come up for auction on Ebay with something like the following description that I've seen recently: "(4) RARE NOS 1966 VINTAGE Motorola.. 2N4264 AUDIO AMP TRANSISTORS"
Let's look closer at some of the buzzwords in the above statement. What do they imply, and what do they really mean?
RARE The seller is trying to make it sound as if there is some additional worth in the rarity of the item. He seems to be justifying his high prices. But the rarity of the item doesn't necessarily relate in any way to the worth of the item. In many cases, in fact in most cases, it can indicate that the reason for its rarity is that it's nearly worthless. People originally purchased very few of the items because it wasn't a good value for the money. Or else most of the items ended up in the landfill as trash. In the case above, the 2N4264 transistor, it has specifications that are so mediocre that it seems to be what was left over after the better transistors such as the 2N3904 and 2N4124 were picked out during the manufacture. These 2N4264s would have been rejected as 'seconds', so Motorola gave them a new number and probably sold them as rock-bottom low-end parts.
NOS and VINTAGE New Old Stock and vintage. Well, you can still get the datasheet for this transistor, and it was still being made as of 1997, the date at the bottom of the datasheet. So if you would prefer old stock over new, then by all means, buy them. But new stock is probably better, and in this case, a lot cheaper. Why? Because the cost of a part is heavily related to the volume sold, so that a very high volume part such as the 2N3904 often costs less than the 2N4124 which has lower specs but also lower volume.
So don't be fooled by "NOS" or vintage terms. They're just another opportunity for the seller to distort the truth. That item that has an inherent worth will be known by others and the bids will indicate this worth. Rather than look for these buzzwords, look for factual information such as date code, or provenance. If they came from a plant that has closed down, they may be production parts that were new when purchased. If you get parts that are still in the sealed bag or container or on tape feed, then you can be reasonably certain that they're new and have not heen picked over.
Motorola Well Motorola is now ON Semi, and you can still get the datasheet for this transistor from their website. And the specs show that it is a really mediocre transistor, literally what's left over after the common ones such as the 2N3904 and 2N4124 have been picked out or 'culled'. Perhaps the seller didn't want you to know that they are still being made by ON Semi, so you wouldn't find out how much of a ripoff he's trying to sell you.
What I've said about this particular electronic part applies to other parts as well, and indeed to anything you buy whether it's from Ebay or from the local store. Even the U.S. government is guilty of doing this. For decades the U.S. Postal Service has tried to convince people to buy commemorative stamps because they're a good investment. Recently I bought sheets of 8 cent stamps from the early '70s for little more than their face value on Ebay, so if you had invested your money in commemorative stamps, you would be getting very little return on your investment.
The motto here is Buyer Beware. Just because people say that it's supposedly rare or worth a lot doesn't mean that it is. Do your research to find out what the prospective purchase is really worth before you put your money down on an item that's advertised to be more than it really is. Make sure that the NOS and vintage really are just that, and not some leftover parts that have been picked over. Your research will later save you a lot of money and grief.