I agree regarding risk profiles.

I known the iron key guys, it's a good product and the team they have is good but it's expensive and doesn't support ECC or at least it did not last year and I highly doubt it supports the curve bitcoin uses.

I think it would be possible to get the interesting scenarios to work on a cheap 10 device, initial probably being around 40 due to volume issues, the form factor doesn't need to be a card there are lots of USB dongles.