I want to be able to have sort of a wide picture, but not fully widescreen because I want to letterbox it. I am not looking for a true widescreen, but a much wider shot because I will eventually letterbox the picture so it "looks" like widescreen.

Can I use a wide angle converter to try to simulate a very wide (in terms of horizontal left to right) picture? Also because the wide angle converters seem MUCH cheaper than widescreen, but I guess they're both totally different.

You might want to read this thread (http://www.dvinfo.net/conf/showthread.php?s=&threadid=18732) since it covers pretty much the same topic...