When you get together to discuss the costs it will not matter if other people over hear this. They will not be witnesses and it won't help you to get lots of other people involved. Please write down all the costs, including your labor cost in black and white. Present it as any business person would do, since that is what you will be for this, if you go through with it. Ask for a deposit up front, at least the cost of the fabric you will have to buy. I think you know that you should not do this and you should listen to your heart. If you don't listen, to your heart then be sure to act as a business person.