It is important to know that you do not always receive the full purchase price. I knew that, but I just read in the negative entries that many were not well informed here.
Without the investment of around 100 euros in 2008, I would have looked in the tube.
But beware: There are certain extensions they do not make sense. For devices which basically have a long life and are little developed, makes no sense (eg: products from Miele)