Gord: I did something very similar to this last month on a spreadsheet where
I had to enter over 6000 entries.  I know what you are doing.  I added two
improvvements from yesterdays code.  first I put in a formula in column M for
the total.  this way if you change the cost or the quantity the total will
also change

Second I added a feature so you can copy cells and the function will still
work.  when I did my worksheet I found I was doing some copy and pasting and
only the first cell of the group was changing.  So I made a little fix.  The
new code has this fix.

If you used my code from yesterday, then simply put the new code in place of
the old code.  Then highlight column I and do a copy and past of I in the
same column.  This will run my macro fro every cell in column I and will
change column M to a formula

Sub worksheet_change(ByVal Target As Range)

For Each cell In Target
  If cell.Column = 9 Then
 
     If Not IsEmpty(cell) Then
        Application.EnableEvents = False
        lastrow = Sheets("data").Cells(Rows.Count, "A").End(xlUp).Row
        For RowCount = 2 To lastrow
       
           If cell = Sheets("data").Cells(RowCount, "A") Then
           
              Cells(cell.Row, "J") = Sheets("data").Cells(RowCount, "C")
             
              Cells(cell.Row, "M").Formula = "=" + _
                 "data!B" + CStr(RowCount) + "*" + _
                 "K" + CStr(cell.Row)
              Application.EnableEvents = True
              Exit Sub
           End If
        Next RowCount
        MsgBox ("Did not Find " + CStr(cell))
     End If
   End If
Next cell
Application.EnableEvents = True
End Sub