I will note that if you don't have certain Kindle devices registered to your Amazon account, you can't buy these. Grr.
BUT! You can download them from the author site (thank you, OP, for the link), so I'm a gonna download and convert and if they work well on the Husband's Nook Color (he's the one who loves these books), I'll send them a donation for all the books.
http://www.projectaon.org/en/Main/AllOfTheBooks
Thanks!