Your bankroll is okay to play 0.25 / 45 player sit & go's. There are people who even start with 5$ and grind these limits. So you have pretty good roll - more than 50 buy ins, 0.10 / 360 players hypers are really good too, you should also play those. Good luck at the tables! Grind freerolls and these sit&go's and you'll be fine. BRM is the key, dont go over limits