The injector replacement cost is heavily dictated by the type and model of the car you have. For some cars getting access to the injectors is fairly easy, and doesn't require much effort from the mechanics. But on some cars, the access to injectors can be so convoluted that the mechanics have to disassemble half the engine compartment to get good access. And when it comes to car repair, it's those work hours that can drive up the price of even simple fixes. Unfortunately in this case, the injectors themselves carry quite the price as well. And because the number of injectors are tied to the number of cylinders the car engine has, you can end up paying a very hefty price for those V8's and beyond.