Ridiculous, how? Bids are too high or differences between them? Who's pulling the permit? Who's insurance, if needed, will be used? If you're doing the demo, and other parts of the job, and some ting comes up that you're not ready, who pays?
I charge an hourly rate on labor and pass my direct cost, matrials and subs, on to my clients.
Doing this for over 25 years and I still find it amazing people don't question paying $90/hr to have their car repaired but question anything over $50/hr to work on their largest asset.