Ohh ok, you are using mac computers/software.
I cant really find anything in your price range that I would put faith into, even with USB 3.0. I also searched thunderbolt enclosures, but as if by magic all the results 2x-4x in price.
Here is the only 2 inexpensive enclosures I would feel like at least as the potential to be reliable for you:
http://www.amazon.com/Tripp-Lite-SuperSpeed-Enclosure-U357-002/dp/B00IOXVX7Y/ref=sr_1_6?ie=UTF8&qid=1436563565&sr=8-6&keywords=2+bay+enclosure
http://www.amazon.com/Rosewill-Enclosure-Removable-RX305-4B/dp/B00S7UTX26/ref=sr_1_8?s=pc&ie=UTF8&qid=1436562436&sr=1-8&keywords=2+bay
Neither of them are firewire though. Only cost effective one I could find with firewire was MediaPro, a brand I have never even heard of that only got 2.5-3 stars.