Earlier this month, Amazon began selling the ClarionMiND MID for $600, $50 off the original MSRP set last fall. Today, the white and red navigation-focused slates equipped with an 800MHz Intel Atom processor, 4.8-inch WVGA touchscreen, 4GB SSD, microSD card slot, built-in speaker, Bluetooth, and Firefox-based web browser are selling for just $530. The black unit (below), presumably because it's the most popular choice, costs about $28 more.
The ClarionMiND is still holding steady at $650 just about everywhere else it's sold (Crutchfield, Buy.com, J&R), so if you're looking for a compact MID primarily for use in the car, Amazon is your best bet.
I had a positive hands-on experience with the ClarionMiND at CES 2009 and wouldn't mind having one for the new car I may be shopping for soon.