5-5 Bankroll Buy In Advice

[TheGame1020]

I used to play in this 5-5 game at one of the poker outfits around Pittsburgh. I was an average winner in the game and I played maybe 20-30 sessions. This game is very passive especially post flop and is full of donks. I quit playing in this game pretty much to focus on online poker 3/6 and 5/10 limit and now I want to get back to this game. My questions for you all are:

What is a proper bankroll for NL? (I datamined for this, yet could not find.)

I actually bought in for 200 when I played in this game, my friend who has success in this game also normally bought in for 200. It seems to work well should I buy in for more less, is this okay if it works? (I ask this because my sample size is small for this game)