I never buy from any airport "duty-free" shop. I buy duty-free in-flight. Just do a price comparison. If I want some newspapers or chocs for the flight I get them at the bus station shop prior to heading to the airport. All other products should be purchased long before your flight. It involves planning. No big deal. Try a local pound store. Why you would wait until you got to the airport to get your precious moisturizer, I cannot fathom. I dislike with a passion the layout of so called duty-free shops after passing security - it's just a time wasting trap for the gullible.
At one period in my career I was involved in my airline's duty-free products operations. This was mid 80's. A miniature of scotch cost us $0.18 for duty-free sales.