I used to be a demonstrator and basically the reason that Tupperware is so expensive, as well as the lifetime guarantee, is the quality of the plastic. It is the only plastic on the market that really lasts the distance without going brittle, i.e. it takes a lot longer to decompose than other plastics, so as well as the product lasting, you also don't get the toxins that get produced as the product is breaking down going into your food. itms. (On a side note, this also is the reason why we're told not to reuse bottled water bottles - because they're designed to break down quite quickly. Same with re-using takeway containers.)