Bridge of Birds by Barry Hughart - an amazing standalone fantasy novel.
from Amazon:
Number Ten Ox comes from a village in which the children have been struck by a mysterious illness. He recruits Master Li to find the cure and comes along to provide muscle. They seek a mysterious Great Root of Power, which may be a form of ginseng. Of course, nothing turns out to be as simple as it seems; great wrongs must be avenged and lovers separated must be reunited, from the most humble to the highest. And even in the midst of cosmic glory, Pawnbroker Fang and Ma the Grub are picking the pockets of their own lynch mob, who are frozen in awe and wonder. --Nona Vero
If you like authors such as Terry Pratchett, Douglas Adams, etc, try this book.
Availability as an ebook: Only from the dark side, I'm afraid..