20 buy ins is pretty much the widely accepted bankroll requirement. I wouldnt recommend moving up to a new untested level with only 10 buy ins. The bets are larger, you will be intimidated for a while causing you to make mistakes and / or played a little scared...and theres a good chance you will take a hit at the beginning.

One you lose 3-4 buy ins, youre going to be sweating bullets if you only have 10 buy ins. I suggest waiting until you have 20 and then mentally seperating 5 buy ins from your roll and then move up. if you lose the 5 buy ins, move back down until you win that amount back. Rinse..repeat....until you are aboe to stay at the higher level permanantly.