Hi Valentin,

Have you considered splitting the research phase and the development phase? You can quote a fixed amount for the research phase (I'm sure you can estimate this in weeks and take the hit if you go over). You can say to the client that you will quote the development once the research phase is over.

Plus, they can take the research phase output to other providers if you do not or cannot do the work or the quote is too much.

Call me to discuss further if it helps.

Kind regards
Stuart