For a hard case, I just went to a dollar store and picked up a plastic box-shaped pencil case for $1.70, tax in. I wrap my KT in a small hand towel for shock and rattle protection, stick it in the pencil case, and it's good to go. I can stick it in my laptop bag, or in luggage, or a backpack, etc, and I feel that isn't going to get damaged or scratched during normal usage and movement of the bag.
What I'm looking for now is a good, light case or cover for the times when I won't be transporting it under rough conditions. Something that would allow me to insert it into a smaller thing, like a pouch or purse.