Fusion will likely have much MUCH higher operating cost. Fusion reactors are fearsomely complex things that will be too radioactive for hands on maintenance. They will be operating at much higher levels of radiation damage and thermal stress than fission reactors. That all adds up to a reliability and maintainability nightmare. The fuel being cheap doesn't mitigate this.

Also, the need to replace major reactor components many times over the life of the reactor, due to cumulative neutron damage, will itself cause very large operating costs.