I understand your thinking. I have worked construction for over 30yrs., done a lot of side jobs on my own. I have allways given more than what I contracted for, allways.
My thinking has been, give up something here, get a lot more in return later.
I never addvertised my work, it has been through word of mouth. I have been very busy over the years also.
If I feel I need to spend $40.00 on something extra for a job, I am very certain that money will come back,multiplied.