Since you are expanding your bleachers (I don't think buzzer-manager takes that into effect) you might what to keep your bleachers at 12 dollars or maybe raise them to 13. 14 just seems a little drastic to me especially with an expansion on the way.
I also think that attendance starts of a little low in the beginning of the season (if you are not coming off a promotion bonus).
The other prices that buzzer-manager seem to be in the right area though.
I would probably recommend getting to 10000 bleachers before upgrading any of the other seats, and then go from there.