Answering the question of what we really need is essential to living a simple life, but let me expand on it first.
What is really necessary to fulfill God's design, call and purpose for your life?
For example, maybe serving Christ means it is necessary to have an $85,000 education to become a lawyer who will defend assaults on Christian living. In that case, your wardrobe would have to be appropriate for a courtroom too. It might be necessary to take clients to lunch and so an expense account would be required as well. These would all be legitimate needs for you to serve God as He has called you.
Maybe you are called to work in the "blue collar" section in American life. Your clothing would probably not include a power suit and your education would probably be much less expensive, but your mission is no less important.
The question is again what is necessary for you to simply be the person God called you to be?
What material things are necessary for you to fulfill His plan for your life? What are you doing with the resources that He provides for you to serve Him?
Our lives are about Christ, what He wants for us and what He wants to do through us. Everything else is a distraction and probably unnecessary.