15-20% depending on how you feel about the service and what you're combortable tipping. For a $300 service, it should be somewhere between $45-60. Of course, if the service was very bad, you could decide to tip less or not at all. If service is acceptable, I would not tip less than 15% though.
*Poster formerly known as Bailey422*

Here's all you have to know about men and women: women are crazy, men are stupid. And the main reason women are crazy is that men are stupid. ~ George Carlin