The miniature NanoPi R5C has a quad-core Arm A55 CPU stuffed inside a 2.5-inch square metal chassis. It starts at just $49 for 1GB RAM/8GB storage, but $10 more will get you quadruple that (4GB RAM/32GB storage).
Palm-Sized NanoPi R5C PC Starts at Just $49 : Read more
Palm-Sized NanoPi R5C PC Starts at Just $49 : Read more