All of the offers I get from VC backed startups are always ridiculous. They seem to believe that I have to take an economic cut just to help them make it. These days, I talk about compensation first, and then about the project itself. No need to waste a week talking and getting to know the team if they can't pay me a reasonable amount.
After a couple of similar experiences, I too started to mention compensation up front. While it has saved a lot of time, I'm starting to have second thoughts about this approach. The problem is that you don't get a chance to sell yourself to demonstrate why a higher salary might be warranted.
I tested that, too. But I always ended up wasting too much time. I have a base salary of n. If their initial estimate is under that, then I move on. I only talk to those who can at least pay n. Otherwise, its a waste of time. I adopted this system after I wasted a couple of days interviewing with a technical advisor (this title is now a red flag for me).