I realise my main problem is playing in games that are suitable for my bankroll, but my main problem is that I don't really know how much I would need.

I play low-limit sit'n'go's. I would like to regularly play in the $4.40 180 man sit'n'go at Pokerstars, I have cashed in them a number of times, and I have managed to get on the final table twice, but I have not been consistent enough with my meagre bankrolls to constantly be able to play them.

So what is the average amount needed, compared to the buy, to play sit'n'gos?

Also, what is the average amount needed for playing in a MTT?

How many times the buy-in should I have to play a MTT, or a Sit'n'Go? And are these the same numbers I should be using to determine whether or not I should move up a limit in tournaments?