There's a mod story in there, somewhere...
Actually, I end up using an android console for my emulation on the go. Used to have a GPH Caanoo, but that only serves now for my portable spectrum emulation needs! It has one of the best ZX emulators I've ever tried for a console - but that's just an opinion.
Still, I've seen a lot of portable options being made with the PI2 + 3D printing. It's getting serious, I think!