I use an Arctic Zone cooler that I got from Wal*mart as a gig bag/carrying case. I put the power supply and my Relay G10 in the bottom, then invert the 30 and put it with the control panel facing down. There's a bit of a taper on the sides of the cooler, so the 30 fits snugly and doesn't go down far enough to touch the stuff stored below. And there's an upper tray that I invert, which keeps the 30 firmly centered. It's not a 'perfect' fit, but I'm very happy with how it works out. There's also a front pocket that can accommodate a guitar cable or tuner, if you need a little more space.
For a carrying handle, I happened to have one from a Micro Spider. I attached 2" heavy duty Velcro pads to the sides of the amp and the strap. Works great!
Maybe I'll attach a pic or two, if anyone's interested.