Haven't been updating this, but I just ran into this card and bought one today. Seems like the best ratio of price per mh/s. It's currently OOS, but just order one and they'll only charge you once it comes back in stock and ships. One of the nice features about amazon is that some stuff you can still order even though it's out of stock to reserve one at the sale price. I'll also add this to the first post. Btw, if you didn't already know, the 6670 is the exact rebranded name of the 5670.
Gigabyte HD6670 $50 AR @ amazon