Zayn Malik wears hipster sunglasses. These sunglasses are not all expensive. You can get a pair of Zayn Malik sunglasses at walmart. This site offers wide range of collections of unique styles and superior materials Zayn Malik sunglasses. One of my friends told me that many styles at walmart are only in stores, but you can get much information on this site and then decided which one is worth to buy.
Well, I have some knowledge of the guy you are talking about, quite handsome in some ways. So, the type of glasses he does wear on a regular basis is called geek glasses, although sometimes he wears sunglasses. Typically, a pair of geek glasses would be less than one hundred dollars, hope you can afford it. Actually, I recommend some places for you, such as Alibaba, Ebay, Amazon, all of which are nice e-commerce B2C websites full of different kinds of cheap glasses.
There are several pictures online of Zayn Malik wearing glasses, but whether they are prescription or not isn't mentioned. There is some information about them just being a prop. One of the pictures shows that zatn malik wears the hipster glasses. You could go to the online stores to have a search and buy one.