Nobody wants to use rotational media to store the blockchain. A fair comparison is for flash storage cost.
Storage cost of the bitcoin block chain is to high….
Meanwhile cost per gb is down since bitcoins release…
https://www.backblaze.com/blog/hard-drive-cost-per-gigabyte/
Discussion
Depends… not attached to a Raspberry Pi, but there are likely a non-zero number of bitcoin nodes running on RAIDs of spinners