This is the right attitude, i dont know why people's time differs in value depending on the task they are performing, you're still paying that person for their time. I understand that some tasks have a lower general market rate, but if the client specifically wants YOU, then you charge YOUR rate.

Whether the client wants you to create a complicated application doing statistical analysis, make a wordpress site, or sweep the floors, if they want YOU to do it, then they pay YOUR rate.