Create Unique Values List While Overwriting Old Data?

I will copy a report into sheet 1, starting in the same place(A1), on a weekly basis. The headers are: Item, Quantity & Price

Week 1's report shows the following:
Windows 5 $1.00
Doors 6 $1.50
Chairs 7 $2.00

Week 2's report shows the following:
Windows 3 $1.00 (change in quantity)
Tables 7 $5.00 (new item)
Chairs 7 $2.50 (change in price)

I need to have a rolling, unique list on Sheet 2 that will do the following:

- add new line items

- keep old line items while checking to see if the quantity or price has changed.

Therefore, after week 2's report is pasted on sheet 1, Sheet 2 should look like this:

Windows 3 $1.00
Doors 6 $1.50
Chairs 7 $2.50
Tables 7 $5.00

Here's the most important part: There will be formulas in Column D in Sheet 2 that I need to stay with each item. generating the desired result on Sheet 2!