I got a lvl 11 gunner... and I've got one big question.
Where can you buy health berrys?

I saw the little guy at the very top, but it looks like they're cash shop.
I'm able to trade him something for 150hp meat chunks... still have no idea what hes taking from me.
Other than that, how do you get above an A consistently?
I got an S rating once. Almost every other run is a C or B.
Btw, I'm on server ch25.