Serious collectors want more than books

Have you ever found something interesting in an old book? Photographs, or perhaps a note from the author?

It never hurts to diversify your business. Here's an example of a rare book dealer who's gotten filthy rich by trading literary archives -- like notebooks or letters from famous writers.

Like the art and real estate markets, the archive market has gone through the roof, and Horowitz, with his wealthy clients and a belief that books will gain increasingly fetishistic status in the digital age, has helped bolster it.

His clients include university libraries, publisher Steve Forbes, and Martha Stuart, who collects inscribed first editions of cookbooks.

A lot of rich people are collecting all sorts of things these days. The supply of high-point collectible books is finite, but there's probably a ton of archives sitting around in attics and basements, just waiting to be discovered.

Today someone listed an obscure author's letter archive on eBay with a Buy-it-Now price of $3,000. I'll be interested to see if it sells.