With only one completed comparable, I wouldn’t apply a standard percentage adjustment. Use its local price per square foot only as a rough starting point, then price the dated work separately rather than calling everything “average condition.” Asking prices show competition, not necessarily...
A practical first pass could request only six items: exact Montreal location, asking price, year/status of construction, floor plan with the area measurement explained, tenure and recurring charges, plus the sender’s relationship to the owner. Reject incomplete summaries before requesting fuller...