Dropping the SSD requirement (which would have been an extremely poor choice to begin with) then you are still looking at many thousands of dollars and a large, heavy server. But perhaps under $10k altogether for the storage system. Lets assume you built it with Western Digital Red 6TB drives which cost $250 each. Lets say you build a system with 12 of these and use 2 for redundancy in a RAID-type setup. I don't know if 2 is a good number. Maybe it should be 3. Anyway, that is going to come out to $3000 for 72 TB of raw storage. Take away two drives (12 GB) for the RAID redundancy and you have 60 TB. Now I can tell you from experience that using FreeNAS for an operating system and ZFS as the file system, a "12 TB" array only delivers 10.2 TB. Lets assume you use the same FreeNAS OS. That is 15% overhead. So you could expect about 51 TB usable, or enough for just over 60 days video at 4096 Kbps bit rate. As a side note, I'd recommend no higher than 15 FPS frame rate to offset the slightly low bit rate.
So anyway that $3000 is only for the drives. You still need a server with 12 SATA ports, 12 drive bays, and a ton of RAM. The rule of thumb for FreeNAS and ZFS file system is 1 GB of RAM per 1 TB of raw disk space, but you can apparently get away with less RAM for really large systems like this. I'd shoot for minimum 32 GB but maybe as high as 64 GB? I haven't built an array larger than 24 TB of raw space and for that I used 24 GB of RAM. It has to be ECC RAM for optimal reliability, too. The cost not including the hard drives is going to approach $2000 I bet. So $5000 for the entire storage system. And if the data is mission-critical then you might consider building two and setting up some form of automated backup between them. Of course the cost could go up rapidly if you need to put in more drives since that will require ever more server hardware to accomplish. Good luck!
