As soon as I purchased a sewing machine my MIL wanted pants mended. I have no problem helping her as she has always been there for me. But I only mend for her.
Once I made a purse. Someone at church saw it and wanted one, and then another, and another......... Then someone wanted a purple purse. I would go to the shop, take photos, email them to people, have them pick out their favorite fabric, and I would make them. When I was finished with the purple purse, she decided she didn't want it. She said that could not afford it and she had too many purses...one excuse after the other. Now, when someone asks, I politely say, "I'll be happy to make it for you. I'll send you the list of material's you need. Then you can go to the shop and pick out your fabric and everything that you would need to make the purse. When you have it, give it to me. The cost for making it will be $25. "
That weeded out just about everyone! I've only had one person come back with everything they needed. :) And I know that she really wanted the purse!