I've bought 2 different brands. Both have only been ok. With one brand I can't sync. I haven't tried syncing with the other. Over all I'd say they have been worth $5.
I like to have cables in many different places. I keep 2 at work, 2 in the car, one in the bed room, 2 in the back living room, 1 in the front living room and 1 in my daughters room and 2 in my purse. We have 3 iPhones and an iPad Mini. Someone forever needs a charge! I can't constantly be hunting a cable. So I don't mind paying $5 a cable and having a few go bust along the way. If I bought only Apple cables I'd be several hundred dollars in the hole.