Right on, Socalgem! I earn my own money and contribute equally to the household, so what I spend is entirely my business. My husband definitely doesn't understand my purse habit -- he thinks one bag per person makes abundant sense -- but he respects my right to spend my money however I want to.
That being said, while I have never lied to him about what I spend, we also have a "don't ask don't tell" policy. Hubby never asks, I never volunteer.
Although "don't ask don't tell" doesn't equate to "don't know"... you're right that the mutual understanding is most important. Good for you!