They are excellent to sit and mix on. If you want good full rounded sound that will mask everything and make a mediocre mix sound pleasing to the ear, then spend $10,000 on a pair of Martin-Logan Electrostatics.
Accept my apologies ahead of time, but, I fucking HATE when people make blanket statements on products in this manner. They are NOT the worse sounding speakers ever made, and they serve a great purpose. If you don't like them, then thats your perogative, and you are entitled to it, but it doesn't mean they suck.
I'll go with Bob Rock and Mike Shipley and all the rest that STILL use them. Those are the opinions I care about. I was just reading Shipleys forum at Gearslutz, about how he is a speaker addict and has a room full of them, and when he gets a pro job like Shania, or Van Halen, he uses the NS10's. And it's not because they were given to him for free way back when, or whatever usual rhetoric is handed back by the nay sayers. LOL.
As for the price... DEMAND. Simple as that. People are paying a grand for them. If I was selling mine, which I would NEVER, I would ask the same amount.
Joe.