Anandtech has reviewed an early R9 290X:
http://anandtech.com/show/7457/the-radeon-r9-290x-review/
It basically beats or matches the Nvidia Titan in every test available, while starting at around $549 or so.
Now.. someone give me a few reasons why I don't need this card right now, because my brain stopped functioning at the sight of those lovely graphs.