Not sure what your workstation offers, but I bought myself an Icy Dock Black Vortex (MB074SP-B) [1]. It's just a case (internal 5,25", but that airflow! :D) which fits 4x3,5" drives with a 120mm fan in front. Slapped some noise damping feets under it. I then bought two low-profile eSATApd to internal SATA slotpanels [2] and 4 corresponding cables [3]. Works great so far!
And yes, you need eSATA, because the distance between cage and machine might be enough to introduce read/write errors. That's what I had, because I used normal SATA cables before.