That would be sexy find if it'* a 428. Depends on mileage, interior...etc. (You know...) Fixer upper, yeah $3,000, that'* for a 400 ci. If it'* an excellent 428, no more than...$7500??? Let me look it up.
Check Kelley Blue Book, or [urlhttp://www.nada.com]. I've heard good thing about nada, simple user friendly, and accurate. I don't know how old they can date back though.
Have fun...let me know how much you bought it for, if you buy it.