Funny, the 8TB drives I was looking at for a new NAS in a few months are around $300... I'm still debating between a 4 or 5-drive nas... but lets say, including the cost of the nas device I'm paying around $2k for 24TB of reduntant storage solution. 24TB of ssd storage alone will cost me over $6k, let alone the cost of a more expensive base NAS box, meaning 7-8K. That's upwards of 4X the cost.
That's the difference between something I can cover from my tax return, to something I won't really even consider. I won't save $6k in power in a year, or 5 to make up the difference, and I don't need the extra speed, to feed media to my htpc.