Here's what we want: We want to work on cool problems. We want to make software that solves problems. We want to make enough money to live comfortably. We want to love our work.
Hopefully, in three months, we'll have some of what we want, and be on track to get the others. Someone buying the company from us may change those things in lots of different ways, depending on the situation.
Our question is, how do we quantify those wants? It's not clear to me how to do so. One approach may be to quantify other factors that would lead to us getting what we want - such as the amount of money we'd want to start another startup.
I could just give something in the ballpark, but it wouldn't be particularly accurate. For instance, I could say that giving away the site we love to work on is worth x, but if someone asks me why not x-1 or x+1, I won't have a good answer.