Seagate released a new 500GB hard drive at CES 2015 called the Seagate Seven. It is a 5mm spinning drive inside a minimalist housing for an overall 7mm thin hard drive.
It is bus powered via USB 3.0 and comes with a 3 year warranty. It is only available in 500GB capacity.
The Seagate Seven retails for $99.99. Check it out here at B&H Photo.