I've never seen them that low to NYC, but it's a rule of thumb: if you can plan in advance, you can get best seats for the best prices (or super low). That's how I travel Acela business class, if I know that NYC trip is coming up in a couple of months or so.

I had to travel to NYC recently on a shorter notice (4-5 days or so), depending on time of day those tickets were very affordable as well (I think I paid under $100 total) - just have to leave early/come back later.