This is both an example, and a plug for my friend Mike.
He's a brilliant creature artist, having done work for games, books, etc. Since individual art books (featuring a single artist) are generally a hard sell without the name recognition of say Rockwell, Mucha, Frazetta, etc., he decided to self publish a book of drawings and sketches, marketed to fellow artists and fans.
Here's why this works:
1. Targeted, niche audience that he can reach through his own website and blog. Since I'm already familiar with Mike's work from other venues, I know how tasty those sketches are going to be.
2. I know the book is going to look good; beyond the interior, I know the cover is going to be laid out well.
3. The content is something that is of interest to that audience.
4. The price is right. While it seems high compared to something comprised primarily of text, the price point is well within the accepted range for a book of illustrations (not to be confused with an illustrated childen's book - we're talking art books here).