Advanced English Dictionary defines good for you as:
An exclamation of encouragement or congratulation. "You got married? Good for you!"
It is usually used sarcastically.
ABC’s E-C dictionary translates the phrase as:
which doesn't really work because people don't necessarily have needed to done anything to get a nice "good for you."
A Chinese English Dictionary gives:
I have been going with a sarcastic ** 恭喜你啊** but it doesn’t seem to accurately express this idea.