There are so many variables in terms of BR management, for instance:

1. Reason for playing poker
A. Professionally- I would assume 40-50BI's for a level +6 months of living expenses
B. Side income- 25-30 BI's for a level, move down when you have 30BI's for the lower level
C. Recreationally- 10-15BI's for a level, you're here for fun right? Might as well play as high of a stake as you can
D. Dwarfman-20BBs
2. Playin ability
-How good are you really? What is your true winrate? Have you gotten to where you are today like me (solid winner+rb/bonus) or have you survived solely from bonus/rb?
3. How often do you cashout/plan to cashout?
4. etc
5. etc
6. ...