A good deal is when you feel good about it really. I would just look at all the carriers that fly out of Salt Lake and then price them all out. Also, some carriers may not put their prices out on sites like Orbitz, so make sure you check their websites (I believe AA is one of those airlines). Just see a price range, and see what you are willing to pay, and try and get under it.
Also, it may be cheaper if you can fly out on a thurs rather than a sat?
For me, $300 would be a good price if I were to fly from LAS to NYC. $350 would be my max. And if I can get it under $300, it be a really good deal to me. But this is just me personally. It may be different for you.