Joe,
There is almost always a few boss 9's for sale on the forum
www.boss302.com, go under the boss 429 section.
also Jeremy Feller has most of the first hand knowledge on the sale and condition and history on those cars, he runs the boss registery... He is a great guy and can be tons of help. if your really interested in talking to him send me a PM and I will send you his cell phone number.
Good luck on the hunt !!!!
Mike