lot's of people come to the micro cash game tables to take a cheap chance thats why it's easier to grow your stack. people will make a 2$ call all in easier than a 50$+ call.
I usually sit down at micro tables with 75% of the max buy in in this case 3$, but will try the low buy in for a change that way you will get a lower loss if you fail but an easier call from opponents on big hands.