New regulations or old, I have witnessed twice numbers going as high as $3500+++ (next flight, hotel, etc) CASH or so in limited situations in the past. Both for Business Class and both being extreme oversells just prior to big events - the kind where people were paying over $10k for an Transoceanic Business Class travel - and they had 4-8 more passengers then they had seats and everyone had relatively high status.
The question is whether the airline has a responsible adult around (read supervisor) to make the decision, UA could have gone much higher in their offer, but it would seem that the GA made mistake after mistake which compounded......