There were a few chromebooks that ran on ARM chips. Not sure about sturdy, but they were definitely cheap. (And, you can enable developer mode and then use whatever flavor of Linux you like.)

Also, the Microsoft Surface RT tablets were ARM and fairly impressive from a hardware standpoint (sturdy, nice screens, etc.) You should be able to get a used one on Swappa fairly cheep. I know there was some credential leak recently, but I'm not sure if that's gone far enough to make it a useful development machine. (Also, it's a tablet with a kickstand and a detachable keyboard...)