In response to a similar question from an investor asking how Berkshire (BRKA, Fortune 500) would invest differently if it had only a few million dollars to put to work, Buffett advised him to think small. "That would open up thousands of opportunities," said Buffett. Earlier this year there were "very mispriced bonds" that "we could buy nowhere near enough of to make a difference to Berkshire," but a smaller investor could have exploited. "Most of the opportunities would probably be in small stocks or in specialized bond situations."

http://money.cnn.com/2008/05/03/news/companies/buffett.am.wrap/index.htm?cnn=yes