Apparently, this was the day you put out all sorts of bulky trash.
Not really paying attention, I suddenly came across this treasure:

... but, even more importantly, this thing was lying in the street, staring at me:

I felt an adrenaline surge - better grab it fast! And sure enough, a minute after picking it up, the garbage truck rolled around the corner:

I took the keyboard home, and I'll be damned, it worked perfectly! Feels just like it should!

I got it cleaned up:

It even still had its model sticker and turned out to be a 1987 model:

It is identical to one I recently came across in the classifieds, at an asking price of 1250DKK (~ 200USD). These things are expensive over here!
Goes to show, getting a bit of fresh air is good for something.