Just reminded this morning after a shopping run. Half price shampoos, conditioners, hand washes and other lotions.
Look at the list of contents. The biggest item is usually "aqua". Water to normal people.
Don't throw out the old bottle. When you buy a new one decant half of it into the empty one. Top up both with tap water. And defy your CEOs, MDs, erindoors or daughters to tell the difference. There is none and they are just as efficacious.
Keep the savings for the essentials like whisky or beer!