My answer is a little like the "Rule of 3" from American Pie, I take the number of knives I have and divide by 3. 
In all seriousness, my wife knows how many knives I have. It’s like any of my other obsessions, as long as the money comes from disposable income it doesn't really matter what it’s spent on.
In all seriousness, my wife knows how many knives I have. It’s like any of my other obsessions, as long as the money comes from disposable income it doesn't really matter what it’s spent on.