I've gotten 24 BP with my high score of 118,347 on Ula'ula. I've noticed that there's a large gap between 10 and 11 BP. I believe that you get 11 BP if your score's around 70,000, but I'm not sure.
Edit: Just beat that high score. Now it's 125,409. I got 28 BP.
Edit 2: Uh. Why do I keep beating my high scores? 162,026 and 50 BP.
Edit 3: It definitely caps at 50 BP. Now I'm at 185,284 and that's the most BP I've gotten.