Sub summdata()
Dim FSO
Dim TheFolder, TheFiles, AFile
Application.ScreenUpdating = False
Set wb = ThisWorkbook
Set FSO = CreateObject("Scripting.FileSystemObject")
Set TheFolder = FSO.GetFolder("C:\temp\svod\") 'Каталог, откуда суммировать
Set TheFiles = TheFolder.Files
For Each AFile In TheFiles
If UCase(FSO.GetExtensionName(AFile.Path)) = "XLS" Then
Set xls = Workbooks.Open(Filename:=AFile, ReadOnly:=True)
wb.Sheets( 1 ).[aj2] = wb.Sheets( 1 ).[aj2].Value + xls.Sheets( 1 ).[aj2].Value
'сюда добавить аналогичные строки по другим ячейкам
xls.Close False
End If
Next
Application.ScreenUpdating = True
End Sub

Sub summdata()
Dim FSO
Dim TheFolder, TheFiles, AFile
Application.ScreenUpdating = False
Set wb = ThisWorkbook
Set FSO = CreateObject("Scripting.FileSystemObject")
Set TheFolder = FSO.GetFolder("C:\temp\svod\") 'Каталог, откуда суммировать
Set TheFiles = TheFolder.Files
For Each AFile In TheFiles
If UCase(FSO.GetExtensionName(AFile.Path)) = "XLS" Then
Set xls = Workbooks.Open(Filename:=AFile, ReadOnly:=True)
xls.Sheets( 1 ).Copy After:=wb.Sheets(wb.Sheets.Count)
xls.Close False
End If
Next
Application.ScreenUpdating = True
End Sub

Sub summdata()
Dim FSO As Object
Dim TheFolder As Object, TheFiles As Object, AFile As Object
Application.ScreenUpdating = False
Set wb = Workbooks.Add(template:=xlWorksheet)
Set FSO = CreateObject("Scripting.FileSystemObject")
Set TheFolder = FSO.GetFolder("C:\temp\svod\") 'Каталог, откуда суммировать
Set TheFiles = TheFolder.Files

For Each AFile In TheFiles
If UCase(FSO.GetExtensionName(AFile.Path)) = "XLS" Then
Set xls = Workbooks.Open(Filename:=AFile, ReadOnly:=True)
xls.Sheets( 1 ).Copy After:=wb.Sheets(wb.Sheets.Count)
xls.Close False
End If
Next

arFiles = Application.GetSaveAsFilename("Результат", "Excel Files (*.xls), *.xls", , "Сохранить объединенную книгу")
wb.SaveAs arFiles

Application.ScreenUpdating = True
End Sub

Sub tt()
Set FSO = CreateObject("Scripting.FileSystemObject")
For Each AFile In FSO.GetFolder("C:\temp\svod\").Files
'work
Next
End Sub