They were selling for a little over 300 a few months back. I bought one but it's still in box looking for a purpose.
Yeah, prices and availability have been all over the place recently.
I plan on using mine for a [dedicated] NAS to replace my Drobo 5C: I have a newly purchased Antec P101 case ready, and an LSI HBA on it's way, and six 8 TB WD REDs ready....
Now it's the hard part; choosing between Unraid, FreeNAS or Proxmox...*
* lots of reading and playing with test setups, but still not decided yet; I have a min-ITX, four 4 drive FreeNAS setup I've been testing for past few weeks [with some old spare drives], and I've been using my old Ryzen workstation/gaming box to test out Unraid and Proxmox this few days...