In my opinion, whenever you play a cash game either online or live, you should always buy in the maximum that you can afford for that session or match the biggest stack on the table. The reasoning is you can wait a whole session sometimes without ever catching a hand. The odds of you catching a hand while someone else does with a decent stack size are rare...so you don't want to let a golden oppurtunity pass you by when it happens. As everyone probably knows, maximizing your winnings is the mantra of poker. If you are uneasy of losing the maximum buy in, you are playing in a game that is too high for your limits. Step down to a lower limit game and buy in the maximum. Your game will flourish in the long run.