Here is another way to look at it........
When someone wants to commission you to make a quilt for them and you give them a reasonable price for handcrafting them a nice full size quilt.
They look at you like your nuts because they could go to Cracker Barrel or BB&B and buy a quilt in a bag for 1/3 of what you just quoted them.
Your not going to give your work away and your not going to give them the materials at your cost. Your going to mark the price of materials up 10% and charge a fair amount for your labor.
Why should the guy repairing your sewing machine do it for free and charge half price for parts. You are paying for someones knowledge and expertise in that field just like you would for an auto mechanic, Dentist, Doctor, etc..
Like I stated earlier I service vintage machines and I charge a very fair price and the work that I do to them is over and beyond the call of duty compared to other sewing machine repair shops. They blow out the dust, oil it up and put on what ever part it needs and there you have it.
I tear them down to nothing more than just a case and start back from there.
Kerosene Spa treatments are a standard with me. As I put them back together I am cleaning and polishing every single part on the machine. I set the tension with a gauge top and bottom, and always include a piece of broadcloth with the stitching under the feed dogs to show you that it has been tested and runs like it should. And they never leave my bench without a good final polish!! :-D :-D
Billy