Ugh: I just chucked a few 1.5 TB HDD's into an old PC and put on Linux, SSH, SFTP, and Samba. cost was $0 not counting the HDD's. It'll eat up electricity (that I'm paying 1/3 of) equal to the cost of the drobo in at least 10 years, after which, I'll have replaced it, I hope.
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Still, it's a good price for a NAS.