I don't sneak anything in. I don't hide how much fabric I have but he doesn't look in my stash closet and probably has no idea. Hell would freeze over before he told me what to buy (or not buy). And I don't monitor his purchases.
I think it makes a difference that we have pretty equal salaries and we keep our finances separate. I pay college educations; he pays mortgage, insurance and utilities. We each pay our own credit card bills and share other major expenses. No fighting about money at our house. It works for us.