Sorry. Use said "passive" bookshelves in your original post. That means unamped. And the 2nd link above in that first paragraph is to a pair of bookshelves that are regularly $80 a pair down to $50. That Pioneer series and the new versions of it that Best Buy carries (check their website), are considered some of the best values in speakers in their price range.
I haven't heard the Audioengine A2s. I know that they are popular, but I believe that they might be hyped because of all the advertising, too. I stopped using amplified speakers for my desktop setup several years ago. Sorry. Not much help with that.