You can get the later model, black painted NOS bars from somewhere (Speed&Sport, I think) for $69.99.... I can't remember the exact details, but they're not exactly the right bars for all of the models that they're listed for - at least one of the models actually has a smaller diameter cross-brace tube. (I was told this - not my discovery!;) )
This $700 "or best offer" asking price smacks of "let's see what happens". I don't reckon that they'll sell for $50, but its obvious that the seller isn't expecting anyone to pay $700.