The raw shrimp method uses a regular shrimp from the seafood department. If you do that place it in a pantyhose foot or something so when it decomposes you can remove it easily. Also you don't have as much control over the ammonia levels.
I've used the pure ammonia method myself. I got it from ace hardware as you cannot use ammonia with any other additives in it.
here's a quick article to check out
Cycle your salt tank