So an extra $1600 to run 4 of those in RAID-10, and even that would only provide around 175 usable gigabytes of space. So this company would be selling the entire RAID10 array's space (your 160GB) for $50/mo. (I know you're not paying $50 for the VPS, but that's just to make things easy). It would take them 3 years just to pay for the drives, and not any other aspect of the server, bandwidth, power, support services, staff, etc.
Do you really want me to believe that? You are going to tell me that these guys aren't making any money on these drives alone for 3-4 years? And that's using the $50 figure, which I know you aren't paying, and doesn't include the cost of the cPanel license, cost for the rest of the server, etc.