Everyone will tell u $125 isn't enough if that's ur whole roll. $500+ is more realistic, variance is quite high in these.
As far as learning how to beat them, theres a lot of good info in MTTSNG forum. I also find chilin_dude's thread inspiring when I'm running bad.
yeah, $125 is way too little. 500 should be fine, maybe less when you're already a experienced player. you can use tableninja if you want to multitable (20+ tables)