Looking for cat door insert for a NON sliding door

Hello,
Not sure where to post this, so taking my best guess

I want to adopt a kitty to keep me company in my apartment. I don't have a sliding patio door, just a regular one. Since I am currently renting, I cannot cut a door into my patio door.

I want a door because I don't really have a good indoor place to put a litterbox indoors. If no such insert exists, is there an odor free solution for an indoor litterbox?

Does this really work? Sharper Image Ionizers are known to be somewhat of a scam.

although i dont want to suggest you let your cat outside due to all the dangers out there for our kitties. Have you thought about buying a cheapo screen door that will lock (deadbolt) andhaving it installed over your door? That way you can put a pet door in it if you really want to and then when you move out just take the door with you. Ask your landlord first though. Most are ok with it. Other than that, i would try the product Hissy linked to. I will say that if you scoop daily and change the litter on a regular basis you shouldnt have much of a smell. I have two cats with 3 boxes and one is behind my recliner in my living room. Its literally 3 feet from me right now and it doesnt smell. My BIL (who has cats also) was amazed when he asked where my litter boxes are and i showed him the one in the living room behind the recliner. He said there is no litter box smell at all in the living room.

Good luck!