Dan's book seems to be selling pretty well going by it's amazon ranks.
Paperback
#656 in Books
#1 in Books > Self-Help > Anxieties & Phobias
#4 in Books > Health, Fitness & Dieting > Mental Health > Anxiety Disorders
Kindle Version
#3,485 Paid in Kindle Store
#6 in Books > Self-Help > Anxieties & Phobias
#56 in Kindle Store > Kindle eBooks > Nonfiction > Self-Help
#93 in Kindle Store > Kindle eBooks > Health, Fitness & Dieting
Paperback
#656 in Books
#1 in Books > Self-Help > Anxieties & Phobias
#4 in Books > Health, Fitness & Dieting > Mental Health > Anxiety Disorders
Kindle Version
#3,485 Paid in Kindle Store
#6 in Books > Self-Help > Anxieties & Phobias
#56 in Kindle Store > Kindle eBooks > Nonfiction > Self-Help
#93 in Kindle Store > Kindle eBooks > Health, Fitness & Dieting