What follows now may be more or less adequate for use in all areas of interest. Hold in mind that some areas may be affected more than others:
Think about the following: ever since online platforms like eBay came up in 1995, the market has changed in a very drastical way and prices for items may change under 24 hours. Books require a certain updating before going through print processing and even with modern day digital prints, a book may need weeks before it is present in all stores. By then, prices will have changed more than once.
Magazines are a better media as they are printed in a higher frequency. Still that is not actually enough in some areas ... actually, even specialized sites nearly working in realtime are pretty often totally wrong, their 'specialist systems' being just as (un)reliable as the semi-intelligent software used for stock brokerage - they only play with numbers, after all. Hence they do not recognize bidding wars, advertizement gimmicks or simple fake auctions.
That said, the only semi-reliable aid is a lot of experience in your specific area of interest and common sense. Becoming adept or even semi-pro is nothing achieved by just owning two books and having a subscription to National Geographic. Sounds rough, I know, and you probably think I am a real nutcase.
However I have seen a lot during the past eight years in this business, and I *only* deal with German porcelain. A few examples come to mind, like the perfect Meissen centerpiece (in box, with documents) with a book value and online appraisal of US$ 4,600. The seller was not able to sell it, letting the price slip as low as US$ 700 while relisting it for two months. It finally sold, a mere month later succeeded by the same item, in damaged state (!), which went away for US$ 1,840 ... impressive enough, but still *far* under 'book value'.
Or the insanely bloated prices for Hummel figures. Even today, many reference books use the same old prices valid in 2004 even though every everybody should have noticed by now that Hummel prices are far below room temperature ever since Goebel (the manufacturer) went turtle back in 2006. They had to sell the rights to save their butt, however the market simply died and even the new proprietor is close to closure. Hence relying on a book value in that sector would be economic suicide.
I could go on and on, but the conclusion is that *if* you really want to start off somewhere, concentrate on ONE area of interest. Read everything you can on manufacturer history and facts *before* even considering to buy your first item, even more so if big $$$ is involved. At the same time you will probably get a feeling for fakes and reproductions, something mostly *not* mentioned or explained in a price reference book. What use is a reference book (e.g. on Roseville pottery) if you, as user, can't see the difference between a true original and a recent Asian reproduction?
Anyway, a certain gut feeling for prices will be achieved over time and slowly become your best friend. Next to this forum, of course
