Here are the NL vs AL results as of today:
League 1 (NL +16 wins)
League 2 (AL +6 wins)
League 3 (AL +14 wins)
League 4 (even)
League 5 (NL +24 wins)
League 6 (AL +28 wins)
League 7 (NL +10 wins)
League 8 (AL +10 wins)
League 9 (haven't started interleague play yet)
League 10 (haven't started interleague play yet)
League 11 (haven't started interleague play yet)
Overall: AL is +8 wins over the NL. Conclusion: Total team salary doesn't correlate to wins.