I don't really follow all your math on this, but I think you are basing your calculations on selling out every game by reducing your ticket prices as you build more seats. Trust me this doesn't work. In BB ticket sales are mostly affected by two factors. The first is team perfomance in the games before your next home game (usually an away game). If you are the best team in your league, then you shouldn't have any problem winning your games and keeping your fans happy. The second factor is the unrealistic curse that the BuzzerBeater gods have decided to place on the top teams in each conference. For some reason your fan attendane is also closely tied to the quality of your opponent. So even though you are undefeated and your fans are singing your praises, if you play the bottom teams at home, your ticket sales are going to suffer. I promise you will not sell out against the 8th, 7th and maybe even the 6th place teams if you are the number 1 team.
So because of this I would say bank as much money as you can, find a good arena price calculator (there is one on the NT database site) and just change the ticket prices without adding more seats and you will do well.