Function func(ByVal значение As String, ByVal дата1 As String, ByVal дата2 As String)
   Dim sdf As Range
   Dim sdf1 As String
   Dim sdf2 As String
   Dim sdf3 As String
   Dim sdf4 As String
   sdf1 = "'C:\Таблицы\["
   sdf2 = "C "
   sdf3 = " по "
   sdf4 = ".xls]Лист1'!C4:X450"
   sdf = sdf1 + sdf2 + дата1 + sdf3 + дата2 + sdf4
   func = WorksheetFunction.VLookup(значение, sdf,  2 , False)
End Function

Sub func2(ByVal значение As Variant, ByVal дата1 As String, ByVal дата2 As String)
   Dim sdf As String
   Dim sdf1 As String
   Dim sdf2 As String
   Dim sdf3 As String
   Dim sdf4 As String
   sdf1 = "'C:\Таблицы\["
   sdf2 = "C "
   sdf3 = " по "
   sdf4 = ".xls]Лист1'!C4:X450"
   sdf = sdf1 + sdf2 + дата1 + sdf3 + дата2 + sdf4
   
   Debug.Print "=VLookup(" & значение & "," & sdf & ", 2, False)"
   Range("A1").Formula = "=VLookup(" & значение & "," & sdf & ", 2, False)"
   
End Sub

Sub sad()
    func2 """Февраль""", "01.03.2007", "18.06.2007"
End Sub