I just placed an order with Buffalo Arms. They have the cases for the original Spencer for $95 for 50. or $2 each.
I'm sure they have the cases for yours too.
I went $$$ for the cases now because they may go from 'hard to find', to "Impossible to get', really soon.
All we need is another law to make reloading supplies harder to get. Midway will not even ship here in MA, because of the impossible wording of the state law. When I called the State for clarification so I could get brass etc, they said they could not understand the law and I should hire a lawyer to read it for me. This is the state that made the law!.....
So, buy the brass and pay what you must.... I'd check your supply of Blackpowder too while you're at it.
good luck....Ken