How much does one of those cost?
It depends on the configuration. "Fugaku" is the $US1.2B flagship machine at RIKEN, which has ~160,000 nodes.
Their two-node FX700 rack server costs about $US40K (which you'll eventually be able to buy from Penguin Computing).
From the article it appears that Canon bought a single 650tflop FX1000 rack, which has 192 nodes.
So if you ballpark $20K per node then you're looking at ~$US3.8 million.
Given that Canon is the flagship commercial customer for FX1000, you can bet they didn't pay that much for it.
However they probably paid at least 1/3 again the purchase price for setup & maintenance services. Supercomputer clusters are not exactly turnkey commodity IT devices (although Fujitsu is angling to make the "little" FX700 pretty easy to get up & running).
To put things into perspective, for pure CPU compute (talking apples to apples, not GPUs here), a cluster of amd64 dual-EPYC 7742 traditional 1u servers crams about 280tflops into a similar rack, so Fujitsu's A64FX has almost 2.5x the compute density of the best amd64 CPUs you can get your hands on at the moment.