Icy Dock has a deal on the MB990SP-B. It’s $14.99 with Free shipping and Icy Dock has a $10 rebate on it.
If you’re not familiar with this little jewel it allows you to stack two SSD or 2.5” drives and slide it into a 3.5” drive bay.
See the Icy Dock website for more information on it.
I checked this deal this morning and they were backorder. Seems it's back in stock and ready to go. I just picked one up myself!
Thanks to Lux for the heads up on this one.