The recent valuation expansion on Price to last reported BV which now stands at 1.22 is worrisome. Last year price to book dropped to 1.0 and any buybacks if where to engaged won't trigger till 1.1x or 78.7...The charities selling and Buffett/Munger age can't be ignored.
I'll assume that the point that you're trying to make is that at yesterday's prices BRK is not currently overvalued.
BRK-B closed yesterday, 9/10/2012, at 121% of most recently reported book value.
But paying 121% is not something a buyer should be proud of. After all, the man who built the company and understands it better than anyone else on the planet, has implied that his MSRP is 122%. He is on record as being a willing buyer at 110% and, during a moment of duress at this year's annual meeting (Q&A #33), a possible, but reluctant buyer at 115%.
On October 4, 2011, Bloomberg (Andrew Frye) reported that: "Buffett Likens Berkshire Repurchases to Buying Dollar Bills for 90 Cents".
“If I can buy dollar bills for 90 cents, I’ll buy them,” Buffett, 81, said today at Fortune magazine’s Most Powerful Women conference in Laguna Niguel, California. “I want to warn the people that are selling to me that I believe I am buying their dollar bills for 90 cents.”
That very clearly implies, at least to me, that HIS estimate of intrinsic value is 122% of book value, that's his 110% buyback price divided by 90%.
I really believe folks enjoy losing money.
They overpaid for the NASDAQ and the S&P 500 in the fall of 1999.
They overpaid for BRK in the fall of 2007.
And, without a doubt, they will once again gladly overpay for BRK in the fall of 2012.