Flip's was the cheapest public Kirkham 427 sale that I can remember, but this Kirkham 289 FIA was sold by Paul at the Autokennel for $74,000 and it was right near the bottom for sale price, though it had s small of amount of aluminum repair done from what I heard:
http://clubcobra.com/forums/showthread.php?t=95139
If one has patience and can wait, be in position to pounce, then there are deals that come along infrequently.