On a side note, a few years ago I worked with a company (as a project owner) that only works on a daily rate base. However, what they offered is that they creat

On a side note, a few years ago I worked with a company (as a project owner) that only works on a daily rate base. However, what they offered is that they created an estimate, that contained, among others a 30% 'risk buffer' and their offer was that if they use that up (in addition to the base bid, of course) then they'll reduce their price to their cost (0 profit) level. Which basically means that it only covers the salary of the developer (plus the office space, supporting staff, etc.). That meant a 33% reduction at that time from their prices, which is nice to in case of a project overrun, and of course is a kind of a warrant for the client that the company will do its best that the project is on time and that the estimate is accurate. I still use the same idea/format when rarely doing estimates for potential clients, but I'm not sure how well it works with freelancers. Whether they can figure out a '0 profit' reduced price for themselves. (Maybe that could be calculated based on the 'if I work 8 hours per day, without any holidays/sick leave/spending time on new project' assumption.) The point is that it should be convincingly low for the client, but not extra cheap.