Originally Posted by apecush
A real injector cleaning involves the removal of the injectors and ultrasonically cleaning them using an appropriate solution. This typically costs arond $20/injector + removal/re-install.
Cleaning is not for carbon, it is for varnish and other deposits from the fuel. The injectors are generally not exposed to combustion carbon as they are in the intake tract not the actual cylinders.
And not necessary, I wouldn't do it at your mileage.