Nodes don't need to store data, and they can be PXE booted if they have a little RAM, so they only need redundant devices for their system partitions if you want to boot them locally (how often will they really be rebooted, though?). A hard drive plus a flash / USB drive would be plenty.

Consumer NASes have been around for 20 years, now, though, so I think most people would just mount or map their storage.