Total Item number by number and cost seperatly

I would like to see if anybody could help me on this. I have a work book i am just starting to work on which I want to add up the total cost of each item number and assign it to cell H4(the orange cell. I want the item number to go into G4(Blue cell) My problem is that people can add orders to this worksheet and I wand to be able to separate out item numbers and totals for each. I have uploaded a workbook and there is an example to show what I would like. I need this to be dynamic as they add to this all day. Any help would be greatly appreciated.

thank you so much.