Yibn wrote:this one is numbered sub 100.
Which really doesn't mean squat... Unless it's like, a prototype, or #1, (or there was a significant tech. change after a certain value) serial numbers mean nothing. Frankly, when it comes to vintage, later is almost always better (simply because it's younger). It really bugs me when sellers try and turn a "low" serial (what does that even mean?) into a sellable feature.
I also wouldn't be put off by the "computer" issue moremagic is referring to--once you've bought like 10 monosynths, maybe you'll come to care (or not), but it's not gonna matter for now. But you might also think what else that much money could by, and what you're looking for specifically. The new Sub37 will definitely be less than $1500, and probably has twice as many features/more reliable. There's also the new studio electronics stuff which is like half the price (though you'd need a keyboard).
In the vintage realm you could also easily find contenders like the Octave Cat, or Moog Source, or original SEM, for less.
Not trying to put you off the vintage vibe (or an Oberheim), but the OB1 (imho) does not quite sound as good as it should. It seems to be stuck in a weird place between the 4-voice/OBX and OBXa territory. I sort of see it as more of a real niche mono than a jack of all trades sort, and you're definitely paying for the "rare" factor.