Cost and Recommendation to Replace 2013 Prius V Engine?

A few hybrid mechanics have told me that I have to replace the engine in my son's 2013 Prius V (230,000 miles). The estimates are $3,500 to $5,700. Is that a fair price in Los Angeles? Can you recommend a mechanic to do the job (or any mechanics to avoid)? Is it even worth replacing the engine (the body has a fair number of scrapes but is otherwise OK). Thanks.