Hi there,
I am a new Mustachian so take my advice with a grain of salt. :) But I'm also a former-anti-mustachian-pro-consumerist. What has helped me most to "see the light" is actually reading simplicity & minimalist blogs and books. Miss Minimalist, A Minimalist Woman, Courtney Carver, Leo Babauta. All are great IMO & I think have a lot of MMM-ish principles.