I bought these Fram CF10218 cabin air filters but sold the car before they were needed so I'm selling them. They contain baking soda and are carbon-infused to reduce odours and sell for $34.99+ tax ($39.54 total) each at CTC. They fit several years of Mazda3 and Mazda5 and possibly others, but it is your responsibility to ensure compatibility.
$25 each or 2 for $40.
If the ad is still here, I still have them.