Try the bestseller lists at Publisher's Weekly (http://publishersweekly.com), New York Times, USA Today etc.

However, as to ACTUAL figures per book, publishers guard these closely. Best of luck if you're an author trying to figure out how many they actually sold. (I think a popular romance publisher is currently involved in a class action suit with some of its authors because the authors maintain the sales figures on the royalty sheets were... ah, creative, shall we say.)

Re:
> For example, if you'd like to reach people
> who love Great Danes (a breed of dog), you
> might be able to estimate the potential size
> of this market by the sales of mainstream
> books about Great Danes.

Great Dane breeders would know. Email a few breeders, you'll find them online.

Ditto for any other niche market. Ask the people involved. ;-)

Good luck with it.

Cheers

Angela




Digital-e --- Info to go