I would go no more than 12,000 bleachers for div 5.
12,000
1,500
300
17
This would be a good set for you. I would probably build 12 more luxury and then set the price for 400. Then 200 more courtside and looking around 60 price? I can't remember.
Also look at some of the leaders of your country in Div 5. See how they price tickets. $6 for 9000 seats seems cheap. I think I was charging 7 or 8 and was selling out 9600 last season. $6 tickets is probably a right price for 13,000 seats.
Just make sure you have a good enough roster as well to win your div next season. If you have to, hire some 32+ older guys early next season just make sure they are good players so you can get out of Div5.