If you're looking for an image tank, I can recommend the Apacer Share Steno. I have one. It came with an 80 GB 2.5" disk for a measly 180 euro. The Apacer case itself is about 70 euro (here in Holland , that is). It seems the disk is easily replaceable, so you can dunk in a larger one when the need arises.
There's no internal card reader but attaching a small one works perfectly. And the USB2 OTG (on the go) slurps up a 1 GB card in a couple of minutes. The battery lasts for plenty of downloads. I got it at the same time I got my R-D1 and sofar I've only recharged it twice or trice.
It doesn't have a preview option, just a teenytiny B&W display that you use to select the mode of operation (download, explore disk, explore USB device, delete, etc).