Have you ever looked into them? I have. Way more money than I have. I would so love one though.
If I would ever play the lottery and win, I could afford it then.
What you really want is one of these; there are instructions on the web for making them, especially small ones to put in a window; you used to be able to buy kits for the small ones:
https://www.youtube.com/watch?v=l9BQ_KeSfW4