| Quote #1
Pennies saved one and two at a time by bulldozing the grocer and the vegetable man and the butcher until one's cheeks burned with the silent imputation of parsimony that such close dealing implied. (1)
To get money for Jim's present, Della has already had to make sacrifices: she's had to embarrass herself in front of various people by being a penny-pincher. All to get a measly $1.87.
| Quote #2
Tomorrow would be Christmas Day, and she had only $1.87 with which to buy Jim a present. She had been saving every penny she could for months, with this result. (6)
Again, we see that Della has already been sacrificing. She's been carefully saving whatever money she can get, and probably depriving herself of various smaller expenditures to do so.
| Quote #3
Suddenly she whirled from the window and stood before the glass. Her eyes were shining brilliantly, but her face had lost its color within twenty seconds. Rapidly she pulled down her hair and let it fall to its full length. (8)
This sudden "whirl" of Della's seems to be the moment in the story at which she first comes up with the idea of selling her hair. That's why she goes to the mirror – to have a look at it one last time. We wonder if she's ever contemplated this possibility before. She seems more excited by the possibility of giving Jim a gift than sad at the thought of losing her hair.