Killing
You are getting a hatchling baby corn right?
If so, you'll be feeding pinkies which is an arguement if they should be killed in the methods I'll list below or if its o.k. to just freeze them live for later use.
Adult mice/hoppers/whatever can be killed by
Co2 - not cost effective for one snake
Or by putting a pen or similar shaped object on the back of the neck and pulling the tail hard to kill them, this is a instant death if done properly but it takes practice.
You can also whack them by hitting their heads on something hard, once hard and fast but this can be hard to do correctly without practice, and in the beginning you're mice will be messy, take two hits, etc. But after a couple tries its easy to get the hang of, and you can do it instantly, without blood.
Dry Ice works as well, same idea as Co2.
bmm