Hey!
$1,700 already paid + $830 refare = $2,530 which I think is as low as you can expect to see TATL these days. Even if that's just a one-way refare, implying the full r/t is $3,360, that's still a pretty good fare.
Not sure how much this plays into UA's algorithm, but on some airlines (LX comes to mind), the upgrade offers only get really discounted when they think they need to do op-ups, as they'd rather collect a few hundred $ or francs.