When DS9 was young, it was $3/hr, then came along DD7 and it became $5/hr, now with DS3, it's $8/hr.
Real easy money for a sitter here, evenings we go out, the youngest are in bed already and DS9 goes to bed shortly after that. Sitter can watch TV or do homework.
But then again, I am a very strict poppa. I expect them to cooperate with the sitters, or they have to deal with me.
We pay about $10 an hour, which is probably generous for a 15 yo and older kids, but that's about what min. wage is here, and I think taking care of my kids is at least as valuable as flipping burgers. IMO the younger the kid the more care they require, so whatever the local range seems to be, I'd expect top of the range for an 18 mo.