Are expensive water bottles worth it for hiking?

For summer hiking specifically, yes. A 40 insulated bottle keeps water cold 10x longer than a plastic bottle, which matters enormously when you are three hours into a trail in July. Cheap bottles also develop off flavors, leak, and dent easily. A quality insulated bottle lasts 5 10 years with daily use, making the per year cost lower than buying cheap replacements. Invest once, stay hydrated forever.