Yeah I agree that other perks can outweigh the money; see also the comment below about marketing being one of the hardest parts about writing a book. Getting more known now will help future books I write (Nathan Barry is a good example).

I am reaping some rewards of having expenses covered to do workshops abroad. It's not a source of income, but it does make travel a lot more affordable which is great.

Ultimately, I hope that there will be some long-term passive income from the book (and possibly other books). We'll see. :)