I should also note that photographs, like all art and collectibles, are taxed somewhat differently than stock and other financial investments. Thus you pay more on capital gains for art/collectibles. We need to lobby our representatives on this unfair discrimination in this area. The stockbrokers just have more political pull than the art world. Perhaps AIPAD can join with the major art dealers and collectors groups to lobby this issue. At the least, letters/email from you to your appropriate congress people wouldn't hurt. Here is the site to find out your representatives' email addresses and other contact information: http://www.uscongress.com .
By the way, senators Chuck Grassley, IA and Max Baucus, MT serve on the Joint Committee On Taxation. Republican Grassley is also chairman of the Committee on Finance and Baucas is the ranking Democrat. Both seem to be more interested in giving their constituent farmers tax breaks rather than investors interested in art/collectibles, but who knows. If you happen to live in Europe, good luck with your tax mess and your legislators.
And, finally, let me say that I (and those collectors and dealers who gave us their thoughts below) love photography first for what it is: a wonderful obsession with art, history, anthropology, beauty and mystery. Financial considerations should never become the preoccupation or aim of any collector. That is when you are sure to go wrong, but that doesn't mean you should make yourself an easy mark either. Hopefully this article will help you understand how the market works so that you can avoid the major pitfalls and enjoy your own personal collection without losing any money on it.
I also admit that I have no crystal ball and your own guesses may be more accurate than my own, but there you have it: my current take on the photography market.