I found (and ordered) a pair on eBay that are a bit sleeker than the Nashbar model, with a little more ergo bend on the lower bar. 580mm also.

$30 shipped from Taiwan.

Anxious to try them out.

Search 'pro comfort trekking'

EDIT: got the bar installed. Awesome! The 3 functional positions of the bar are all very useful...you can be easily comfortable in all 3.

The sweep on the back bar, also puts wrists on a more ergo position, as opposed to the straight Nashbars.

I double-wrapped for better comfort/grip.