Reading your post, I don't completely understand why you're looking at hard cases. If you're putting it inside another bag, I think a rugged sleeve should be adequate for protection.
To that end, I would look at
this sleeve from Booq. The Vyper has been well-received (you can search these forums for numerous testimonials). I have a Booq PowerSleeve, which I think is excellent.
I hope that helps - good luck!