That's a
massive jump from a CalDigit to the VTrak. You'd also want to note FC drives are anything but cheap. Essentially SAS drives, but cost even more.
I was thinking go with a decent RAID card, and use good external enclosures.
Say an
ARC-1680ix24 (up to 28 drives without using SAS expanders), 3x 8bay enclosures, and the cabling. Beyond that, you'd need to use SAS expanders, but they can get you to 128 drives on this card. If you don't need that many ports, you could opt for the
ARC-1680ix16.
For an enclosure, this would be an
example, though you may want a different format (
rackmount example). Up to you. Redundant PSU's can be considered, and are standard on the rackmount I linked (12bay units, so only 2 needed for a 24 port card).
From the internal ports to the enclosure, you'd need one
these per port. Note, I linked the 1.0m cables on the assumption you'd use SATA drives (2.0m max, for active, which includes all cable lengths in the chain). You might be able to use the 2.0m versions, but it might be unstable (it would have to be tested with the gear you actually perchase). SAS can use longer cables, as it operates at a higher voltage.
It's effectively the same as what you had with the CalDigit as far as how it hooks up, except you will have to have an open slot cover to route the cables off the internal ports.
Hopefully this can give you some ideas, but would be cheaper than the VTrak by a substantial margin I think.

Let me know how you want to go.