match & copy value to last column instead of last row

Mussa

In the attached revised file, the UserForm macro below is modified by the addition of the lines in bold (commented for your help):

Private Sub CommandButton1_Click()
Dim sh As Worksheet, ss As Integer
Dim n As Integer

Set sh = Worksheets("sheet2")

With sh
    ss = .Range("a" & .Rows.Count).End(xlUp).Row
    ' See if Code already exists...
    For n = 2 To ss
        If .Range("A" & n) = ComboBox1.Value Then
            'if so the add new price to the right of last recorded price
          .Cells(n, .Cells(n, .Columns.Count).End(xlToLeft).Column + 1) = TextBox1.Value
          Exit Sub
        End If
    Next n

' If loop completes (i.e. not found) then add new row
    .Range("a" & ss + 1) = ComboBox1.Value
    .Range("b" & ss + 1) = ComboBox2.Value
    .Range("c" & ss + 1) = ComboBox3.Value
    .Range("d" & ss + 1) = ComboBox4.Value
    .Range("e" & ss + 1) = TextBox1.Value

End With

End Sub

That loops through sheet2 to see if a match (first only) is found in column A. If so, it works out the last used column in that row n then adds the new price in the next cell. See Don's tutorial Find the Last Column with Data in Excel VBA to understand the line which writes the new price. It then exits the sub.

If there is no match, your original code adds a new row.

Note too that in  I've cleared the price box in macro ComboBox1_Change by adding the line:

TextBox1.Value = ""

Hope this works for you.

ss = .Range("a" & .Rows.Count).End(xlUp).Row