Ssds may be fast, as the pure storage arrives remain traditional hard drives are still the best deal.
Take the N300 series of Toshiba, which is specifically designed for raid setups in a nas. That was already available in sizes up to 8 TB, but there is coming this month also a 10 TB version.
It runs at a speed of 7200 rpm and offers transfer rates up to 248 MB/s. The disk can have up to 180 TB per year process. Is 10 TB what a lot of good? This series starts already at 4 TB.