My wife is cheap, so my hobby kind of irritates her. But we made a deal early on that seems to work. Every year I get a set amount of money to buy knives. When I first started it was $1000. I could buy two really nice $500, a few $200, whatever. During the year it became a game to add to my budget, she'd give me $100 for my birthday or if I'd do some favor for her, so I usually ended up with more then what I started with. But it worked because she no longer had to ask what the knife cost because all I would tell her was that it was coming out of my budget. As long as I stuck within my budget she didn't care.