If you are buying in the USA please use one of the Aussies over there to inspect beforehand, or you can end up getting one in completely FC.
On the other hand if you are considering buying locally, grab a copy of Just Cars magazine, and start treking around your nearest Mustang importer's showrooms. If they haven't got exactly what you want they will still have good advice, and might even have something to suit on the water. Just Cars will also give you an idea of local prices.
For an idea of USA prices get a copy of Old Car Trader from your local newsagent.