Scholar Dana Frank notes that the women involved in the riots were not the poorest (though they were surely still below the poverty line and those who were the poorest were certainly affected even more dramatically). Their husbands earned between $10 and $15/wk. A Mrs. Ida Markowitz told a reporter that she supported 5 children on $10/wk. Another woman, Elizabeth Broslin, said that she had only $4 a week on which to feed herself and her four children.
So, at the low end of the scale, a monthly income would be $40 and on the high end, it would be $60.
In cost of living surveys from the early 1900s, it was revealed that immigrant families broke down their income thusly:
30% rentAnd of course, this is just one estimate. Others place food costs at 40-60% of monthly income.
30% everything else (clothing, washing, materials, fuel, light, medical services, insurance, recreation)
It is also important to remember that women shopped for food nearly every day. There was not place to store food aside from perhaps one small shelf -- refrigerators were a newfangled idea and far too expensive to actually own. So not only were these women on very tight budgets but they knew exactly how much each item on their grocery list cost and were acutely aware of any changes in price.
Consider that at one point, people were buying "loose" (or unbottled) milk $0.01 or $0.02 at a time!