As the author clearly stated in a comment, this is more of a proof-of-concept for learning ceph, not for a real deploy as it’s not meant to be cheaper per GB, but cheaper for initial cost: a “3 figure cost of entry way to begin learning ceph”.

Even today  (year 2017) an x86 based solution will have a minimum cost much higher while giving higher performances (129€ just for a single CPU board plus case without memory and storage)