Best bookshelf speakers

Dynaudio Emits

I would recommend the KEFs. You'll be hard-pressed to find bookshelf speakers in that price range that image better and they provide fantastic detail. However, as decent as the KEFs are with regard to bass output and extension, there are better options in that regard. You can find RBH 41-SE or better yet 61-SE speakers on the used market in your price range. They are just about as detailed as KEFs with slightly less "edge" vs. the KEFs. And their aluminum woofers output way more bass than drivers that size should. But if your primary focus is bass output and extension, I've never heard speakers that can best Hsu Research CCB-8s unless you opt for something much larger (be it a monitor or a tower.) Those also have a coaxial driver, so like the KEFs, you should get superior imaging if you set them up properly. (The Hsu's are at or beyond your declared budget new, but you have 30 days to try and return them if you end up not liking them.)

A MTM design is likely your best chance at getting big sound from a bookshelf on a modest budget. 

You might want to take a look at the Martin Logan Motion 35XT Bookshelf Speaker.