“We’ll keep you in mind for future projects”

That has to be one of the cruelest things you can say to a consultant. If you didn’t accept what I proposed this time, are you expecting me to change the next time you come around? Maybe you’re using me for a cost comparison, which really insults us both.

Maybe just give me some constructive feedback on my proposal, thank me for my time, and we will both go on our way.