The only way to truly 'copycat' Buffett is to buy Berkshire. Even if large investors like him are buying on the open market, they won't say so until they have to, and by then the price has generally already risen. 
Following Buffett on this one, even if a retail investor pays more, will likely still pay off handsomely. Financial companies are Buffett's wheelhouse, and he prefers to buy for the long term. This is a vote of confidence in the company by the smartest kid on the block, who is willing to put his cash on the table. If the shorts want to take on Buffett, God rest their souls.