Best deal is at Kobo, at least on the enhanced version. Free at one time without the bonus content, still free in PDF form.
Click
HERE to get it for $1.99 at Amazon
Click
HERE to get it for $1.99 at B&N
Click
HERE to get it for
$1.59 at Kobobooks (and enter their contest to get a free Kobo Reader).
Click [PDF version at site is illegal - Moderator]