j'tote is expensive, but will hold a DX nicely. Or any mini-laptop bag, really. . .you just have to find one that has the right dimensions. The small one from Vera Bradley holds the iPad. . .bet it would hold the DX as well.
All that said, I don't take my DX out all that much. Just around the area I only carry my Kindle (Klassic, thank you very much

). When I go on a road trip, I take the DX with me cause it's the one my newspapers/blogs/magazines go to and they really do work better on it than the Kindle. I was flying a couple of weeks ago and elected not to take the DX -- instead I switched the WaPo subscription to my Kindle for the weekend -- and I was reminded how much better the navigation is on the DX. But I digress. Anyway, when I do take the DX with me, it goes in my j'tote or other laptop bag with my laptop. It lives, in general, in it's Oberon cover.
Also, you know those portfolios you can get that have a notepad on the right side and a pocket on the left and zip up all the way around? The DX fits just fine in such a thing. Doesn't have a carry strap, but it is some protection. Mostly they're basic black, (with a company logo sometimes, 'cause they're done up to give out free) but I bet if you look you can find fancier ones.