You just need to look for Apple certified cables. They don't have to be from Apple. Just be aware most certified lightning cables aren't a great deal cheaper. I suspect the license to get the certification is not cheap.
If you're in the Northwest, it's not infrequent to find Fred Meyers to have 20-30% off or so on cellphone accessories.
And the Belkin cable is also pretty good. As I recall, the lightning connector is even about the same size. (The size of the covering on the cable end is generally the big worry point on Apple Certified cables, as some of them are bigger and don't fit through case openings.
I got the Belkin cable for $10 at OfficeMax since it was on sale, even the cheap cables sold at TJ Maxx are 14.99. The Belkin cable does have a larger connector so it might be an issue with some cases. Reviews are not positive for the Belkin cable, but I've had mine for a month or 2 and it works great. I suspect the negative reviews are for fakes.
Yes there is a marketplace section on this forum, it is not trickery. Be careful with Amazon purchases, looks like most of them are fake and same goes for eBay. You have to get lucky and find someone who has spares from many iPad/iPhone/iPod purchases or purchase aftermarket.
$19 at walmart or bestbuy if you have one of those stores. I believe the cellular stores sometimes sell original lightning cables. att sells their own for $19 but i'd rather buy apple's for the same price.