Generally speaking, not much. I have over a dozen of them and never paid more then $75 for any. Some were free. Neat machines though.
They were also sold under the "Wizard" brand name.
Exactly the same except the aluminum face plate in from has "Wizard" stamped on it instead of Bolens.
I've been collecting walk-behind two-wheelers for 40 years. They're fun, easy to move, and cheap. That is, except for some of the big monsters like Sears Handimans or Standard/Viking Twins. I've always figured that at some point in time, they'd start going up in value. But, haven't seen that happen yet. I still see many get scrapped or sold for $25 in yard sales.