I'm guessing that most people buy their sunglasses at the airport, with the cheapskates buying designer copies at the beach shops on arrival. But if you want some real vintage style, you need to do your shopping early online - and one place worth a look is Klasik.
The site has an ever-changing stock of vintage sunglasses from throughout the 20th century - or if you're in London, you can check out the stock at Spitalfields Market.
We're quite taken by the classic simplicity of Ray-Bans, like these Balorama glasses. They were costly when they went on sale in the mid 60s (twice the price of Wayfarers) and originals from the period are hard to find today.
The pair for sale with Klasik go for £225.