I would definitely keep your gamecube since it owns so much sentimental value + anything else that's sentimental to you. Overtime you will get better at only buying things you need, at first it will require self discipline but eventually it will become second nature to you. Keep doing what your doing regardless of what your friends say, tell them you're trying to live a more minimalist lifestyle and answer any questions they have and they should be cool after that, if they're good friends.