You also have to factor in where you are. SVS ships from OH. Hsu from southern CA. Epik from Chicago. eD from Newton, IA. Rythmik from Austin, TX. Shipping something this large across the country isn't cheap.
A single Empire or dual Legends - http://www.epiksubwoofers.com/products.html# Any of the Rythmik subs in that price range - http://rythmikaudio.com/products1.html The A7-350 is right on your budget - http://www.edesignaudio.com/product_info.php?cPath=2_41&products_id=746 (less if you pay with...
Better - http://www.svsound.com/view-all?page=shop.product_details&flypage=flypage.tpl&product_id=12 Best - http://www.wilsonaudio.com/product_thor.shtml (Price isn't mentioned there but it runs about $20,000).
I haven't heard any of those speakers so I can't give an opinion on them. Just make sure you get the matching center channel. I wouldn't get a sub from any of them though. Pick a sub from a company known for their subs. SVS, eD, Epik, Rythmik, Hsu, Outlaw (designed by Hsu), Emotiva and a few...