You may have already answered your own question. In a recent search I performed myself, decent widescreens aren't found for $450.
You can find lower resolution widescreens, even HDTV widescreens which could work, (but the HDTV's will be considerably lower resolution than a 19" LCD).
To get a good 20-21" would probably run $750 (with a decent resolution for its size).
I like widescreen for games that support it. I have a widescreen laptop and I have enjoyed those games that add some extra peripheral vision, but some games just stretch the screen which is lame.
IMHO, for your price range, I'd concentrate on a quality 19" (or an adequate 19" and pocket the change).