How much do you charge for work where you have to advertise, bill, wait for someone to call, schedule time, pay for gas and tolls to get there, spend your time driving, pay anyone else that helps or works for you, pay for contractors insurance, study to have the knowledge to know what to do, fight with the customer over the charges, buy the tools to perform the job, perform the actual job, risk injury, guarantee the work is correct, then spend your time waiting until the next appointment. Fitting about 3-5 of these jobs in 8 hours.

But I suppose 4 hours of actual work and 4 hours of distraction in an office setting is worth $240 in your mind.