x2
In the day, the 12" RGB was the "cheap" monitor, versus the "good" monitors, which were the 13" / 14" displays - both of which used the same Sony CRT (yes - even though Apple's marketing people claimed one was an inch bigger). The unconventional resolution was a big problem and the dot pitch was fairly coarse. Despite that, they were fairly reliable. Given the number of them sold at the time, I don't think the 12" RGB would be considered rare.
I was quite partial to the 12" monochrome display (I think that's what it was called). No colour, but very crisp / clean image and fitted nicely on top of the LC series and IIsi machines.