There is zero reason to pay Apple's usurious prices for their incredibly average charging cables. You're paying more for literally no reason. Why give a trillion dollar company even more of your hard-earned money?
The ones you get included in the box, ok, no problem, especially since most of them are now braided—Apple seems to have learned a lesson there. The silicone-jacketed ones are pure garbage, though. So cheap. I just leave them in the box.
The Apple Thunderbolt cables are quality, and pricing tends to be similar across brands because of the complex build and certification requirements, so I'm less likely to take issue there, but even then, at least Anker's fully-certified Thunderbolt cables go on sale often.