Would you like to make you house smell good without having to constantly using sprays, candles, plug-ins, etc? Just pick up an essential oil of your liking and drop 15-20 drops on your new air filter at time of installation. Your scent should last about thirty days when it is time to change out your filter for a new one! Every time your air blows you will get a waft of that lovely scent you dropped on!
I love peppermint and think it smells so clean, so I picked up this bottle at Whole Foods for $10. The $10 bottle should last me a few months so I think it's well worth the money!
Note: make sure to vacuum out your vents with each filter change. It helps with air flow and reduces the amount of dust blown in your home! Enjoy!