I ordered all the parts I needed for mine from datakey. The case came from Home Depot - a nice 4x4x2 gray plastic outdoor junction box. At $6, the box cost as much as the rest of the parts put together.

I find accuracy is quite good until speed gets faster than 1/200s (.005s) or so. Audactiy's resolution is only to .001 second, and the time to open and close the shutter becomes a significant percentage of the total time.