Looks like it is a dealer part and they sell the complete terminal shoe, if this is what you need 30656851 is the part number of the picture, there are two versions of this terminal shoe: short for cars with premium sound (bigger battery) and a long one for cars with standard sound system(smaller battery)
If it’s only the bolt. Advance Auto Parts sells this not sure if it will fit perfectly, maybe some modification will be needed.
The bolt broke- I may drill it out and tap it and thread something in place- There is a ton of snow outside and don't feel like biking to a parts storehttp://https://photos.google.com/photo/AF1QipOELuotIwJmWzuQhCdlNERUtdBLS3iHaaPm2axt
Okay I fixed it I drilled a hole through the thing and put in a new bolt- it isn't steel or aluminum or pot metal, it was actually fairly hard as I planned to weld a bolt in place but that wasn't going to happen