Thank you for all your replies, NSK. I do appreciate them.
Can you explain what the PM is that you refer to?
Yes, I agree with you about NVPH's "scheme", though I might argue it wouldn't just apply to them. It would also apply to other catalogue publishers who try to do the same kind of thing.
Yes, I see they did provide the technical information. That's very good, though it seems that it only serves the technical philatelist, instead of supporting the market. To encourage market activity in the field, you need people buying/selling/trading material, which seems unlikely to happen if they have no idea of value/scarcity of what they have.
That's why I indicated it seemed like "new" information. Even though it's 7 year old information now, it seemed new in the sense that it hadn't been published before. I wasn't sure if it ever appeared in any small, privately-published books or pamphlets that sometimes are printed before information makes it into full catalogues. I hadn't found any indication of that though, but I'd probably need to know the right Dutch words to search find any mention of it online.
The thing is, if they did put the prices online, behind a reasonably-priced subscription, after ceasing to put it in their catalogue, I'd seriously consider subscribing to access it.
Regarding your comment on pricing disinformation: I understand what you mean, but pricing still can be an indicator of relative scarcity, and give the market a backbone to build off from. Collectors and dealers can use the prices as indicator, but still adjust what they charge or pay based on condition, availability, personal experience on how hard something is to find....as they do with mainstream catalogue prices.
I suppose I'm a little sensitive about barriers to information, due to discovering how fragile philatelic information can be, even in this age of the Internet.
Some examples being 3 books I've been trying to source over the last couple months on Algerian, Morocco, and Tunisian postmarks. There are very few references to them online, let alone finding a copy for sale. The Algerian one was easiest. There was an
ebay listing (more expensive), and a French dealer's website (cheaper). French dealer never responded to my messages about shipping costs, so
ebay won. Morocco book was OK, but is still in process. No copies are for sale anywhere, so I contacted the author, and he had no copies left to sell. He did offer to make a copy of his personal book for a price, which I agreed to. He "lost" his PDF file of the book.....
The Tunisian one is proving the hardest, and is still in process too. Copies are not to be found anywhere, and contacting the author did not work (he might have died). One person I contacted had a copy he made of the book the author had loaned him, and so I guess getting a copy of the copy is the only option.
And that's not the only one I've ran into either. I was looking for a while for a book on Ceylon postmarks, and couldn't find a copy anywhere online. I ended up getting it from a retired dealer in the UK who had it within a philatelic library he had disposed of a 4-5 years ago, but that did not all sell. I only found it because Google found the title in a PDF of an old list of the books for sale. The dealer had to take a while to dig it out of the boxes of books he had packed away.