I'm testing a new app which seems like the perfect choice for broke artists (costs 0$) looking for great line control. It's called FireAlpaca and it has everything I loved about MangaStudio for skecthing and it's even better depending on what you're looking for (for instance I really hate how the undo command in MS will go back and drop so many distinct line strokes considering them as one action that is SO annoying! FA only goes back 1 step back at a time). I just spent 10mn setting up the shortcuts and it was good to go.
It is no MS of course, but what it does, it does really well and it's using only a fraction of the RAM MS does while doing so which is nice especially if you work on a small config as I do most of the time (laptop).
2 first done with FA (last one is MS from April)