This is really what it comes down to. A corollary, for me, is "will razor x for y dollars make me happier than the ones I already have?" Sometimes the answer is yes, often the answer is no.As for "how much is too much", I think my purchases were all reasonable. And that is true because I am satisfied with those purchases.
I was mentally going through my modest collection and realized that I have only exceeded $200 on two razors. And yes, they were both worth it to me.