Last year I went to an expo that had a booth from Aetherbyte. At the time one of the members told me about their difficulty with getting MSX cart shells. Turns out that one vendor hiked up the prices when they found out an American company wanted them. Glad at least we get this game in digital form (for now).
http://retrogamingmagazine.com/2018/01/06/inferno-launches-digitally-on-msx2-gaming-computer/