Swedish Alga AB made the "John Ericsson" steam engine probably from mid to late 1970s and as far as we know, only made this stationary, single acting steam toy engine with a piston diameter of 7.5mm and 20mm stroke.
A rare find nowadays. Some think it resembles a nuclear power plant, like the Wilesco R200. Original John Ericsson accessories (grinder wheel, lathe and transmission) are very difficult to find.
If you're looking for a John Ericsson for sale, don't forget to click on the German flag to search in Germany.
What's it worth? Take a look at this Alga John Ericsson price guide: sold listings for a value indication.