These are search engines to help you find the place that's selling the book you want at the lowest price. Works for books in all e-reader formats.

AddAll ebook search

Inkmesh

These stores sell epubs, which are able to be read on all e-readers except the Kindle

Barnes & Noble NookBook Store

Borders ebook store

Sony Reader Store

ebooks.com

ereader.com (A Barnes & Noble company)

Fictionwise (A Barnes & Noble Company)

Kobobooks

Powell's Books

These stores sell books that work on all e-readers, including the Kindle

Baen Books (Sci-Fi)

Smashwords

Kindle Only

Kindle Store