This whole testing fiasco is really a wonderment. To lose that many precious (and expensive) chips to only gain a marginal amount of useful information is insane. At any company I have worked for that kind of decision would have landed someone a pink slip.
To be fair, the cost of a processed 65nm wafer is likely somewhere between $1500-$2000. Not exactly a fortune.
Avalon pays (it is estimated) about 4k per wafer at 110nm.
How is BFL paying half that at 65nm? Somehow your estimates sounds kinda off.