That's kind of ridiculous for a software write blocker.
According to the white paper, this product specifically is used for 'compliance archiving' and other situations where data needs to be archived in an immutable form, but allow for fast and random access once mounted. And the RDXLock software has to be used in order to read the data back. This implies possibly some form of encryption, or some proprietary filesystem?
I can achieve the same effect with a disk dock, a handful of drives, and software that encrypts the data being put on the drives. (assuming the same software is also used to decrypt and read the drives later.) and for a lot less money.
I can see this being useful with companies that have already adopted RDX as a backup medium or archival medium; I don't see a good cost benefit if one is switching from, say, LTO or other types of offline /archival media.