Totally agree with 5LM!
For myself I started out at the lower end in order to get families and then moved up from there. The lowest in my area is $25 but I started at $28 (have even seen $20 but not sure how they manage it). The highest at the time was $30 and now slowly there are more and more between $30-$35. I doubt there would be any demand for higher especially when licenced centers are around $18 - $22 (I think).
I do find it great that there are more in my area upping their fees so that the rest of us can follow suit. There has to be a limit though and it would all depend on the area.