Update/refresh button

I have some thoughts about making a command,button or whatever that can ease my pricelist adjustment job.
I have a price list of about 1000 rows. At the end of each row I have a cell with the actual price for the actual periode. The thing is that I update some of these prices once or twice a month. But now i want to add a new column where I type in the new price as I get it. Then when I have all the prices I need I was thinking about using a command button that will insert the new prices, that I have typed in, into the cells for the old prices. Like an update/refresh button actually.
Is this in anyway possible? Do you excel pro's understand what I want to do?

All answers appreciated

I hope this helps to explain a little:

<-copy from sheet->  <-copy from cells->      <--paste-->  <--paste to sheet--> <-paste to cell->
Sheets("New Prices").Range("A1:A15").    Copy Destination:=Sheets("Price List").Range("I1")

So to use a command button for your specific example above, first add the command button, then right-click the button and select view code. This will open up the VBE and generate something like this (excluding the green font):

Private Sub CommandButton1_Click()
Range("G4").Copy Destination:=Range("G3")
End Sub

Copy and paste the code in between the lines (I added the green code above for your example). Note that I did not use "Sheets". You can omit the sheet reference if the copy and paste destination are both on the active (selected) sheet. If they are on another sheet, or on separate sheets, add the Sheet reference as noted in the firts post.