Who Makes A Cheap DIY External ThunderBolt SSD Drive Enclosure?
That said, for those who want the utmost in performance (especially for multi-drive ThunderBolt SSD RAID arrays) ThunderBolt is the way to go to FULLY maximize a solid-state drive's potential Read / Write speeds without some of the additional overhead and limitations of USB protocol.
Currently the most affordable choice is G-Technologies ruggedized 2.5" SATA ThunderBolt drive case that comes with a short but integrated ThunderBolt cable that tucks away when needed. Paired with any of the top performing SATA III solid-state drives currently available it's quite possible to come up with a DIY drive for Mac OSX or Apple's TimeMachine for $200 or so.
In the earliest days of ThunderBolt, Seagate's ThunderBolt 2.5" drive SLED was the only and most affordable option. You could simply press a 2.5" SATA drive (HDD or Solid-State) onto the standard edge connector and have an instant DIY ThunderBolt SSD drive ready to go.