You can ask for the books on freecycle, and likewise put your jiffy bags on freecycle. I could do with a pile of jiffy bags, but I am sure that its not worth gettting them from you. Someone nearer, who sells stuff via ebay or the like would be delighted though. Plus, as other commented, buying them new is good for the publishers. Suppliers of science textbooks is a business deserving our money, unlike the unutterable tat most people waste their money on.