Any project that picked, is much more beyond a tool. It involves people, process and tooling — a one-time effort initially as well as a recurring effort post that.
TCO refers to measuring the effective (net) cost that would be spent to reach to. For instance these would be some of the components that would be considered while calculating TCO:
What is the cost of the tool? (Infrastructure + License)
What is the development & employee bandwidth that this will take?
What is the time that this will take to go LIVE? What is the opportunity cost for that duration?
What is the cost to regularly maintain that product?
What is the technical capability required to setup, manage and run this system?
What will be the timeline for which this product can be used in the company without significant re-work/upgrade being put on it?