The suppliers are all using the same sources, AMD, GoodMark, Sherman, Dynacorp.
Shop for best price and , and check shipping costs, as some make up the price savings by charging unreasonable shipping costs.
Your correct, no one makes an inner fender for the A-Body yet.
Check with roger at AutoBody Specialties.
http://www.autobodyspecialt.com/His sheetmetal prices are usually lower then anyone else.
Although mopardave at roseville should offer you a good deal.