$300 is probably okay for the $11s if you're playing one table SnGs. Personally, I'm still playing mostly $11s with around 70 buyins, (with the occassional $22 slipped in) mostly because I am playing two table SnGs and I am trying to learn to multitable. I am very very conservative with my roll though. Do what you're comfortable with, and move down if your roll dips below an acceptable level.