How much does a fusion reactor cost?

Excuse me, could you please elaborate on the estimated cost of a fusion reactor? I understand that this technology is still in its developmental stages, but I'm curious about the financial investments required to bring such a groundbreaking energy source to fruition. Are there any recent estimates or projections available regarding the overall cost of constructing and maintaining a fusion reactor? Furthermore, are there any cost-saving measures or advancements in technology that could potentially reduce the overall expense in the future?