Avg. price increase
 

Hi Chip,

But don't you need to know the number of sold items for each item,
too?

I would try something like this (cells A1:E6):
Item Old_Price New_Price %Increase Sales
A 100 =B2*(1+6%) =TEXT((C2-B2)/B2,"0.00%") & " Increase" 50
B 200 =B3*(1+6%) =TEXT((C3-B3)/B3,"0.00%") & " Increase" 40
C 1000 =B4*(1+6%) =TEXT((C4-B4)/B4,"0.00%") & " Increase" 30
D 10000 =B5*(1+6%) =TEXT((C5-B5)/B5,"0.00%") & " Increase" 10
Total =SUMPRODUCT(B2:B5,$E$2:$E$5) =SUMPRODUCT(C2:C5,$E$2:$E$5)
=TEXT((C6-B6)/B6,"0.00%") & " Increase in total"

You can overwrite C2:C5 and see the possible outcome instantly.

HTH,
Bernd