I have a JVC MP Xp7210....waiting for my Birthday for my One (Blue or White? Can't decide...) My JVC is about the same size as the One and it fits beautifully in a Nintendo Wii bag that I picked up in "GAME" (UK gaming store). It has pockets and space for power leads, mouse, etc and is padded. I bought a cheap one that does a good job but isn't branded...wouldn't want to advertise Nintendo!
Great forum by the way...can't wait to get my One.