Cheap and good do not always go together, but in this instance it does. Straight from supplier, you can buy goods good and cheap. Aliexpress has their own shipping company thus it make it so cheap to send the product from chinese seller to you doorsteps. Choose from good sellers and you wont have issues of receiving faulty products. Even there are chances of bad products, you can ask for partial refund. Aliexpress is the platform that helps to solve the issue as a middleman between buyer and seller.