to play, make profit, be comfortable and also not mind losing a few max buyins in one session you need to have around 50 max buyins for any level......
i have read blogs, watched interviews of so many internet pros and they all say this.
imagine if you have somewhere around 2k. You are playing at 0.50-$1....you get a few coolers or a coupple of bad beats and have a real bad session and lose 6 or 7 max buyins. Then this is about 40% of you whole roll.......
Phill Galfond actually recently said that for the nose bleed games on fulltilt, he always has a roll of 5 million behind him.