Changing your in air cabin filter is pretty simple task. It only takes 5 to 10 minutes to actually change the in cabin filter. I have been to the dealership and they are looking to charge anywhere from 60 dollars to 90 dollars, to save some money and time, you can do it yourself. How ofter should you change it? I change mine every 15,000 miles, but I believe this all depends on your environment. If you car is driven in a rough environment, you might what to change it sooner.
The filter can easily be found on Amazon, here is the in cabin air filter I use for my Prius 2012: