The 12D was, in its time, the "budget deck of choice" among many record enthusiasts. Pioneer sold boat loads of them. Indeed, it was targetted at the price - conscious consumer, but it had great build quality for its price range. It could also, and still does for many, produce quite good results.
I remember the damn things were everywhere, and were usually mated with a Shure (M75? series) cartridge. The results were very good, and people snapped them up. I think its a great testament to vintage gear that a great many of these tables are still around and still being enjoyed.
You might quibble withe $100 price tag a bit. However, if it is a local sale, you have the ability of checking it out thoroughly before you buy it. A Grado Black may be a good match for that table, too, assuming that the Grado doesn't hum. I think the 12D had a steel platter, so there's a possibility that the unshielded Grado might hum a bit. You might check the Grado Hum thread which is a "sticky" thread in this forum.