I bought all my books airside in WHSmith at Gatwick so that they didn't count against my weight allowance, then I left them behind in Turkey.
I bought them on the 3 books for 18 pound offer and made sure I bought a few with 500 odd pages to keep me going for a fortnight.
I know this is not as cheap as buying for 3.99 each in Tesco, but six large paperbacks weigh an awful lot and I prefer to use the weight for clothes LOL.
Me and DD15 also try to pick a two or three we will both read, which saves a bit on weight and money as double bubble.