Generally the line producer had already done a budget breakdown, even if the amounts have to be tweaked once the director decides what he needs.
You'll probably submit what you think of as a reasonable equipment list based on the locations, the schedule, and what the director wants, and then the producer will come back to you and tell you how much over you are. It happens on every show, big and small, so don't worry about it. Once the producer tells you that your package is, let's say, 3X what he had budgeted for, you can work on reducing the list to accommodate, but at some point, you'll probably have to tell the director and the producer that "x" location or scene isn't doable within the schedule without the necessary equipment or manpower, so that some sort of compromise can be reached.
With a budget so low, you'll have to get some answers about some basic assumptions, like will there be a generator or does everything have to work on limited household power, etc. And how many people do that have budgeted for grip and electric -- there's no point in having a lot of equipment if you don't have the manpower to set it up or wrap it.