It's essentially just a fancy SATA to USB converter. You can get a generic one for less than $10. Whether or not it's worth another $15-$20 for a Pi specific SATA to USB converter is really up to you. Personally, if I was connecting a 2.5 inch drive I would probably just use a generic adapter, or an external HDD.
However, on my Pi3 I do have a Pi specific SSD adapter, but it uses the much smaller mSATA form factor SSD and it all fits within the footprint of the Pi3 (whereas a 2.5 inch drive is already larger than a Pi3 before even adding adapters).
Click on the picture for my review of the X850 mSATA expansion board.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?