I think people should remember that ACube put those
Minimigs on sale for 129 EUR. That helps a lot.
As for the AmigaOne 500, it's likely not even Amiga 500 compatible as the name would lead one to believe. However for persons that doesn't have time, but have money. Or persons just plain technically inept to use a screwdriver and install OS etc. It's probably a nice choice if you like everything served. Point being it's a service, not a playfield changer like Minimig or FPGA Arcade.
Custom electronics is expensive. But most of these solutions seems to be commodity computing platforms that gives way to little in the MIPS/money factor. Even if the PPC is a nice CPU.