Amazon with Anker Direct has the 6' Anker PowerLine II MFi-Certified Lightning Cable (4 colors) for $10.99 - $1.50 off with coupon code AKCM6FT4 at final checkout = $9.49 with free shipping on $25+ or with Prime. Also available in a 3' version for $6.79.

Listed as "probably the world's most durable cable", it promises to last 12x longer than other cables and to withstand over 12000 bends.