You probably wont find a new one, it's been 24 years since the last 430's where made. Will most likely have to rebuild one, but most wear type parts should be available.
I have seen a few reconditioned decks show up on eBay/Craigslist. The deck on my 420 has been rebuilt. The deck on my 430 is original paint and in perfect shape. It still has the paint on the underside as well. I was shocked when I looked at the tractor before I bought it how nice and well taken care of it was. By far one of the nicest old tractors I have run across with only 900 hours on it.