In recent years I've noticed a strong connection between the rise and fall of quantities and prices of items on eBay and the appearance of certain books. For example, a book titled Barclay Toys, Transports & Cars came out late in 2004, and by early 2006 I was seeing a marked increase in the number of Barclay toys on eBay. (Barclay manufactured slush-mold toy cars and soldiers from before World War I until about 1971.) Prices were up, too. I expect the slight delay was due to the book not being noticed right away. This is common; most books are not promoted, and it can take many months for them to permeate their potential markets.

As of late 2007, the numbers and prices for Barclay items are still up. This phenomenon had a similar effect on certain kinds of toys from the same era, like Manoil cars and trucks. Interestingly, there was little increase in vintage Tootsietoys and other, later diecast toy cars. Hence, the book's effect was limited to a specific kind of collectible, and not to the entire category of toy cars. A book about NASCAR collectibles would, in similar fashion, have an effect largely confined to NASCAR items, as opposed to the wider range of automobile racing collectibles (the Indianapolis 500, Formula racing, and so forth).

Another, more specific, example of this phenomenon is the increase in the number and selling prices of Crosley-related items on eBay during the first half of 2007. That included anything related to Cincinnati industrialist Powel Crosley, Jr. and his many 20th-Century enterprises, among them cars and auto-related items, appliances, radio receivers, radio station WLW, books, magazines, Cincinnati Reds ephemerae, etc.

I had been keeping a close eye on Crosley items because I am co-author of the biography of Powel Crosley, Jr. (CROSLEY: Two Brothers and a Business Empire that Transformed the Nation). The book came out in November 2006, and the increase in the number of Crosley collectibles hit within weeks. I attribute the faster rise in interest to the fact that CROSLEY got a lot more advertising and publicity than the Barclay book. It also appealed to a much wider audience.

In the Autumn of 2007, however, I observed a drop in the number of Crosley items being offered. There was a definite trend toward lower prices at the same time. The Simplicity of Radio, by Powel Crosley, Jr., for example, now sells for a quarter of what it brought in a couple of years ago. The decreases are most likely caused by Crosley-aware sellers quickly satisfying (though not saturating) the market.

The Crosley rise was paralleled by an increase in the sales of Cincinnati-related items - for higher prices. Interestingly, that market hasn't fallen off.

I'll be following this phenomenon as other books on collectibles and history (including two of mine coming out in 2008) hit the market. This could lead to new marketing strategies for eBayers: if you have a large collection of a specific kind of item, you might try to get a book for collectors on the market to increase awareness and drive up demand.

Of course, that's not possible for most sellers. But you can keep an eye on future book releases, and stock up on related items. Your local library has a monthly publication called Forthcoming Books in Print in which you can look up books on all subject areas. Publishers' websites provide announcements of books a month or more before they're released, and bookstore employees are often aware of new books before the public is. And when you know a book is coming out, you can try to stock up on related items.

The phenomenon is strongest with books about collectibles. Collectibles publishers will continue putting books on the market, and we're going to see more and more category-specific books as people learn how to self-publish and distribute their books. Other categories include the aforementioned history and biography, as well as celebrity bios, industry-specific books (automotive, aviation, and the like), and local histories.

And if you're going to write a book on collectibles, or about a famous person or historical events, think about stocking up on related collectibles, so you can cash in after your book comes out.