I've been able to play with the Foxboro presale a bit, as a U2.com subscriber. It seems there are very few $250 seats. At least, there are $97.50 seats available in the sections nearest the stage, only about 25 rows from the field. So, it seems they're only charging a lot for the lowest rows in the best lowers, then the rest of the lower level is $97.50.
The mezzanine level seems to be $97.50, except for between what would be "4:00 - 8:00" if you look at the seating diagram as though it's a clock face - with "12:00" being the stage. "4:00 - 8"00" is 57.50. The field is 57.50. The bulk of the uppers are 30.00.
It looks as though they're actually being pretty kind with the ticket prices.