I think in practice hardware wallets can't exactly work in such a way that you just buy a turnkey product right off the shelf in this manner. There is no way of knowing that the random number seeding isn't compromised in some way that allows the manufacturer to issue pre-determined private keys. As such you really can't trust a product like that any more than you might a web wallet that stores keys server-side.
The only way a product like this actually makes sense in my opinion as any kind of secure wallet is if the manufacturer produces the unit as a hardware platform with a completely open and documented API, and open-sources the software in such a way that you can confirm the checksum against an independently-compiled build, or where the process of initializing the device involves compiling yourself and loading the binaries directly onto the device.
I'm not tech savy enough to know if it meets the requirements you just listed, but what are your thoughts on trezor. I believe they are open source.
http://www.bitcointrezor.com/Trezor is indeed open source, and looks excellent. Launch got delayed from October to January, which will probably turn to February, but as long as they deliver a solid product, all good. Not sure the price though?
