I kept my cars through many difficult women, and my wife knows this. Rather than being unsupportive she participated. Do we have agreed upon limits for my monthly spending, a budget or allowance? Yes.
Let's put it this way, she supported me going on the Power Tour with my brother "because it was important to me" (her words). She is encouraging me to build a car for Drag Week and go with my brother "because it is important to me" (again her words). Hell she wants us to build a car for the Targa Newfoundland, and wants to navigate it because she wants to be involved.
To put things into relative perspective: I gave her a kid, our beautiful daughter, this year because it was important to her; and there will be a second one in a year or so. Do you know what kids cost these days? When we are done I will look back and say: I think we should have named named them Lamborghini and Ferrari - because that is about what they cost us.
We don't fight about the money and time spent on my hobby (too often) because it is for the good of the family.