That's probably a fair guess. For a SATA drive in a 3.5" form factor at 100TB, I could see anywhere from $600-$800 per TB of space. Even though the interface is SATA, the random IOPS would still surpass any of the best HDDs out there except in the rare case where you might compare a 100-drive array to a single one of these.
This was from the article:
Pricing will be similar to existing enterprise SSDs on a per terabyte basis while offering 85% lower operating costs. Overall, the ExaDrive DC series will cost 42% less per terabyte over a 5-year period compared to existing enterprise SSDs.