As to scratches, I would recommend either laminating the front screen with clear plastic or getting a cling film PDA screen protector and trimming it to size. Get a sheet of laminate (a4 or 8.5 x 11), cut a piece 0.5" bigger than your Karma, place it over the Karma to get an idea of where the stick is going to come through by laying on top a coin of approximately the same size as the stick divot. Carefully remove the Karma from underneath the laminate without moving the position of the coin. (You can tape the coin down if you prefer) Use a sharp X-acto knife to trim around the coin. You should be left with a squarish piece of laminate with a coin size hole in it. Clean the face of your Karma and make sure it's dry. Now, peel the laminate paper off on the hole corner only and carefully position it so it lines up with divot and the rest of the Karma corners. Be careful not to touch the laminate on the sticky side as you will be looking at finger prints for a long time. Once its positioned on that corner, slowly peel the laminate paper off while smoothing it down starting from the corner and working outward. If you try to do the whole thing at once, you'll get bubbles so take it slow. Once the laminate is down and smooth, use your (very sharp) Xacto knife to slowly and carefully trim around the menu button and the outer edge of the screen. Take it very slow on this part keeping the tip of the Xacto in the crack between the plastics. Do not attempt to cut directly on top of the screen or cutout the hole for the divot while its on the player. You will scratch the screen (ask me how I know).

As for cases, I picked this one up on a trip through Heathrow. It fits the Karma well but not too snugly with room to spare for headphones. (I superimposed a picture of a karma on the case...see photo). It has a strap on the back for placing it on a belt. It comes with a neck strap also.



http://www.essentials4travel.com/mall/productpage.cfm/e4t/dsg0013/33407/Design%20GO%20all%20in%20carrying%20case

I also see that Design GO also makes a hard sided case but I haven't tried it with my Karma.
http://www.essentials4travel.com/mall/productpage.cfm/e4t/dsg0014/25595/Design%2DGO%20e%2DSafe%20carrying%20case