Use only as much shampoo, etc. as you need.

Shampoo is expensive. How much do you NEED to use? Cut the amount in half once and add a little more if you need. Test things out and don't accept the prescribed amount from the company. What else could you use less of to make it last longer? There was some big drama against a prescription contact company for saying they needed to be changed more regularly than necessary. See what you can do different.