Yes, I agree, P2 are more effective than P1, but if you only look at the cocktails, P2-3 (6.2 c/stam) is more effective than P2-4 (6.125 c/stam), and the bonus 50 (20 c/stam) gives more than the bonus 80 (18.75 c/stam).
On the other hand, you get 15 bettings points from P2-3 (0.3b/stam) and 30 betting points from bonus 50 (0.6b/stam).
And indeed, on P2-4 you get only 20betting points (0.25b/stam), BUT the bonus 80 gives 50 betting points (0.625b/stam).
edit: Aaand shop is clear, thanks to the race. Now, I can buy those gold ^^