cylinder 4 misfire

What is your question?

I have a 2013 Toyota Prius with 75,000 miles in it. The engine malfunction code on the Prius is “Code p0304 misfire four cyl”. I want to ask how much would this kind of problem cost. Also, an insurance agent is selling me a service contract for $4,500, which includes repair or replacement of this cylinder part. I would like to ask your opinion if this is a reasonable price?