So it's basically a modified A-1 Auto (originally WWSS) with a Cat-in-Space dial (Silver Moon).

The reason that this one is cheap is that I chipped the dial a bit and glued it back.

If you look at the hour marker between 6 and 7 o'clock, close to the inner edge of the case, you can see a white line and that's the part. That. And that it has an NH36 (ENG-JPN weekday disk), instead of the NH38. 

As the case is basically an A-1 Auto, instead of the A-1 Mod Case, there is a serial number on the back. It's 078/100: