So taking the case alone, a lower quality, but comparable 24-bay Norco case usually sells, with rails, for around $475 shipped. That excludes a power supply so falls into "always be good because it's a case" comparison.
That basically means you get the power supplies, SAS controller, SAS expander, and motherboard for $105 shipped. You could get the newer ones but for 24 bays at 6.0gbps you would need three of them to direct attach all of the drives.
For a storage server, you could even use a Xeon E5-2603 which would run about
$120 used. RAM you could get cheap 4x4GB DIMMs for under $100. 16GB quad core 24-bay server.
Realistically, with the boards, the oldest these cases are going to be is about 2 years so quite a bit of life left in them. There is not much comparable given that pricing.