If I look...
at my local source's inventories, then I would have to say, yes you can buy a black powder firearm. You can even find round ball to stuff them with, but you cann't find any size of caps or BP substitute powder. Looking on the internet is pretty much the same picture - except you can still supposedly get 2ff and 3fff black powder in four to six weeks. Many sites are out of Goex but have the German or Swiss brands available. But you have to search. So Yes, there is a lot of evidence of panic buying in the black powder community.