I'm a babysitter wondering Should I ask for a raise? How should I do it?

I babysit for several families, and they set the rate at $7 per hour several years ago. the average rate is about $10 in my area. The kids are not easy (one family has 2 year old twins and a three year old, one is a 3 year old and a 6 year old with poor behavior) I am a really good babysitter: I play with the kids, never do HW or anything until after they're asleep, and I'm 17 and drive myself to and from jobs. Recently, the family with the twins asked me to go to Martha's Vineyard for a week with them, and I agreed to go. I was expecting to be paid about $450 (not sure why, that just seems appropriate to me), but they just informed me they planned on $150. I'm starting to feel ripped off a little, but I am a bit nervous to say anything. I don't want the families to resent me or to lose the jobs.