Roland CB-HPD Bag f. HPD10/20

Well made, ideally suited for your spd-sx, and it has the cool bag for the stand you use to keep up your sampler. It is, however, pricey just like everything Roland puts out, and it isn't really intended to house the spd-sx with the holder screwed into its back. It probably could, but I guess the rucksack would quickly get damaged that way. I suggest getting the hard case with additional space predicted for the holder, if you carry a lot of equipment and don't want to be bothered with screwing and unscrewing the holder onto the sampler every gig.