Apple laptops are more expensive than low-end Windows or Linux machines, but tend to hold their value and not fall apart. (Cheapest of all are Chromebooks, which can be pretty great if you’re willing to live online.) If you’re interested, Apple has a refurb store where like-new machines are sold at a discount with a full warranty. The supply changes frequently.
Your current machine is an 11.6-inch MacBook Air, 1.3GHz dual-core Intel Core i5, released June 2013, if you want to compare specs to newer ones.
And used? The best source I know for used MacBooks is MacSales.
Or, you could buy from Apple and get free wireless Beats.