Can't get my body guy to finish

I've worked as a bodyman for the last 23 years, I enjoy doing restoration work, but collision is were the money is. Everytime I take one on I think both sides feel like they are being screwed, but at the end of the job a figure out what I made after my expenses and I'm lucky to make 1/3 of normal shop rates. I am finishing up a 69 chevelle now I have 300-400hrs in it so far, new 1/4s, doors, fenders, hood, deck, floors, painted the frame ect. He wanted to keep it less than $10,000 with materials which is a ton of money but with 2,500 in paint and material that comes to around 20hr to spend on shop over head and there isnt hardly anything left. So it is easy to take other jobs that pay the bills.