How much weight do you give to Financial Aid in making a decision?

I do not disagree, but to some extent, aren’t many of us choosing boarding school over local public schools despite the cost? There are many full pay students in boarding school. At what point is “better” not “worth it”? I expect that varies greatly on a case by case basis, and is influenced by a multitude of factors. Its a sliding scale, I suppose. I just wonder how much weight others have given cost in the decision making process.