Cheap cables will have a lot of complains from customers and you will lose your accounts sooner or later. Good cables are more expensive so you will have to buy a container to get close to right price but selling container might take you years.
Get a reputable supplier, quality product, reasonable price, establish a brand, get your own product page on Amazon and then you'll stand a chance of doing well with cables.
I know there are many cheap very low quality cable sold from China in alibaba. They may even be harmful to the device. When you sell on amazon, always make sure the quality is acceptable