Retain or Buy Project: Prepare a report regarding Relevant Cost analysis to Retain (Keep) or Buy a brand new car. This is totally up to each student. You decide what are the costs, and how much they are. Every student's project will be different, as everyone has different priorities, costs, and. You decide what are underlying factors (costs) and which ones are relevant for your decision Retain or Buy Project: Prepare a report regarding Relevant Cost analysis to Retain (Keep) or Buy a brand new car. This is totally up to each student. You decide what are the costs, and how much they are. Every student's project will be different, as everyone has different priorities, costs, and. You decide what are underlying factors (costs) and which ones are relevant for your decision