I don't think that the price paid of the new injectors is a bad one. I just believe that the injectors weren't the cause in the first place. With all the sensors in the truck and their technology, it can be difficult to make an accurate diagnosis. If the computer said that the injectors needed replacing, then that's all the tech knows. I had an old boss-man that with a 2000 F150 that started running like crap. After spending a bunch of money on diagnosis and ineffective repairs at the Ford dealership, he took it an automotive electrical specialist who determined that the only problem was a pinched wire in the steering column (where the wheel tilted up and down).
As has already been said, if the injectors were bad, simply clearing the codes would not fix them. Just because the truck is running good now doesn't necessarily mean that the injectors had to be replaced.