The free route covers more than people expect. The Salem Witch Trials Memorial on Liberty Street is free and open dawn to dusk; the Charter Street burying point is 135 m away, about two minutes on foot; the Witch House at 310½ Essex Street is 769 m, about ten minutes, and costs $17 to go inside. The Salem Witch Museum is a seated presentation for $19 an adult.
What the ticket adds is a person who knows the order of events and the people behind each address. The 1692 walk promises the events that led to the trials, the places linked to the judges and the accused, and the stories of those accused; Secrets of Salem adds the arc from a Puritan town to the Witch City across nine stops. That difference — a story rather than a list — is what $25 to $35 buys.
If you are on the fence, walk the free route first and book a guide for the next morning: every walk on this site can be cancelled free up to 24 hours before the start.