Some time ago I was looking for the same thing, and found a lot of complaints about Buffalo drives failing a lot. No clue if that has changed or not. But I settled on a Elgato 240GB, bus powered, SSD, T'bolt drive. Not sure about the price difference. But I think that Baffalo is much cheaper. Also consider a USB 3.0 bus powered drive. Good performance, less cost. What video codec to you anticipate editing with?
Just a heads up theres a huge variance in Thunderbolt and USB3 enclosures - a lot of drive less enclosures have average SATA chipsets and so do a bit of hunting/reading.
I ended up buying a 256GB SSD Lacie Rugged and then replacing the internal drive with a 1tb SSD - 400MB/s R/W. Interestingly their HDD based model that looks identical and also uses thunderbolt doesn't have the same chipset inside and maxes out at around 200MB/s.