I think you might also have problems in playing too high of a buy-in for your bankroll.

At $25 buy-ins playing NL it's a good idea to have a minimum $400 bankroll.

The math on this:
Lets say you push all in on your good hands and win 66% of called all ins. You make a 16% profit here. However, if you have only 4 buy ins, your odds of losing 8 of these hands in a row are .33^4 = 1.1%

Over one month of play, pushing all-in 15 hands a day, you push 450 times. At these odds, you bust out 4.5 times/month (probably less because you are making a profit here)

With a bankroll of 8 buy-ins, you are .06% to bust out. With 12, you are .0075% to bust out. With 20, you are .0000001% to bust out. So generally, you should be safe and make enough profit to cover your ass with good play at about 10 buy-ins.