Do you expect someone to tell how much per person?
Do you eat gebrokt? Do you wash for every meal? Appetites vary
But here is some advice for after yom tov.
every Isru chag pesach we make a list of what we used and the # of users this is a great help in planning & shopping. We also list left over non perishables so we can shop before opening the Pesach cupboards.
In Brooklyn the major kehilos have have reduced price outlets (warehouses, bulk, cash,advance ordering, no delivery) for many pesach staples. Bobov(both) satmar (both) etc. too early for detais.