Clever setup, that's what I call a frugal audiophile.
I was thinking of doing the same thing and use my old over sized iPhone 4 case but the DX50 is just too thick, I am hoping to get a case at one point, so tired of using an old iPod Video silicon case that is still a little too small. I am keeping my eyes opened for an unusual one.
Thanks, but it wasn't so much about being frugal as finding what was available before I got the DX-50 all scratched up! It is OK from a utility viewpoint, easily available (they must have had about 15 of them on the rack, and their website says there are 280+ stores, so it shouldn't be too hard to find one) and, as you say, cheap. Cheap enough that if you need to cut holes to optimise it for the player, who cares?
If someone comes out with a slick case specifically for the DX-50, I'd still be on it...