The lens method is expensive. You can always buy used.
As far as screen size considerations, I tend to go about that differently than the industry standard. I find that I get eye strain if the image is too tall. Width does not effect me much at all. So I suggest you shoot an image on your wall and watch it for a few days. Zoom in, zoom out and screw around with the image size for a while. When you find your 1.78 image size that is comfortable to you, stick with that height. If you wish to go 2.35, again, stick with that height and make it wider. If the 2.35 screen size will not fit, then you should probably stick with 1.78.
