Sorry, but your search continues. I found a post at Rocks in My Dryer asking moms to comment on how much they pay for babysitters. The answers and justifications are wildly different.
As a pre-teen in the early 1990s, I marketed my babysitting services around my neighborhood. My keystone was that I was a Red Cross certified babysitter, which seemed to mean little to the parents I encountered. Anyway, I typed up and printed fliers on our sweet dot matrix printer and targeted those households with children that I thought I would enjoy babysitting, which meant I purposely avoided some households. I could always pretend the flier blew off their door or that I thought they had pets and I had allergies.
My first gig paid $4/hour for four kids ages 18 months to 3rd grade. From then on, I was pretty much locked into the rate of $4 or $5 per hour regardless of how many kids I was babysitting. I never enjoyed a holiday or fiasco tip. In writing that, I realize that it was probably foreshadowing of a work life to come, but I was too green to see it. That I would hold jobs that pay below market rate, that my first real job out of college would include the experience of both getting a bonus and then having it taken back, that all my attempts at negotiating will end in disappointment and that when I am told my new job’s pay expected increase will be 5%, that will be the year they lower it.
That last part is something for my “letter to my younger self” journal/mini-book project.