I, myself, replaced the cabin and engine air filters. Yeah, piece of cake, but I still undertook to do it myself!! Parts cost $35 total, labour took me about 2 mins for the engine and 10 for the cabin.
Pics don't seem to want to upload, but I'll try...
Fwiw, the car is 7 years old with 12,221km. The engine filter was pristine (replaced any way), whereas the cabin filter was filthy.