> What makes this one so special?
It fits in you (man) purse, yet covers the equivalent of 2000+ pages in mainstream textbooks. Also, it covers both calculus and mechanics in an integrated manner (something not usually done). Finally, it's (arguably) fun to read.
RE price: I would price the book less, but Amazon discounts the book like mad, so if I want to keep any semblance of respectability (i.e. above $20) I have to price it at $39. I also setup a 40% discount on lulu for today to match/beat the amazon discount.