Pokemon Sun is out of stock on Amazon but if you're an Amazon Prime member in an Amazon Now area you can get a copy for £27 within an hour.
Download the app and use NOWFIVE as the promo code and you'll get a reduction of £5 from the price of £32. Then choose a delivery time and presto.
I wasn't sure whether it'd work as they've been saying they're out of stock but I placed my order at about half ten and it's just arrived!
I placed the order in North London, so there were probably stocks available in the Greater London area - OR - Amazon are holding out on Basic users and prioritising Prime members.