>Since he is easy to work with, founders sell cheaper.
This requires a source. Many of the companies he purchases are public companies. If they are selling "cheaper" because they like Mr. Buffet, there's a problem.
The important Berkshire acquisitions are entire companies, most of the time private. Sometimes they were public at one point but were taken private before BRK bought them. (ex: Duracell). Sometimes they were public at the point Berkshire bought them (ex: BNSF) but this seems to be the exception.[1]
The public stock acquisitions that they talk about on the 13-F are really a minority of Berkshire's activity, but sometimes he really does get a better price because he's willing and able to negotiate weird deals like the Bank of America warrants.
This requires a source. Many of the companies he purchases are public companies. If they are selling "cheaper" because they like Mr. Buffet, there's a problem.