There's no way I would get $140. for a second hand mower around my area the plus side is a lot of people around here throw out their mower when it's about 3 years old because the air filter is blocked with dirt or the spark plug has failed or just needs a carby clean, as soon as their mower doesn't run it goes to a trash pile ,I once picked up a new mower that had a gum nut stuck on the blade so the mower gave the impression that it was seized.
I've seen tool shops around here selling new ex demo mowers with briggs motors for $100. ,it was a few years ago.
I bought one of the ex demo mowers used it for 5 years and then sold it for $100.
A lot of the time people throw out a good working mower because they would rather pay someone to cut the lawn and if the starter cord breaks.