With regards to the home game, I'm not a big fan of buying chips from the big stack because it essentially taking money away from the table. The $X buy in is no longer a factor in the game which may or may not affect how the big stack plays. The only time I feel that this is necessary is when every single chip is on the table in your set.

This is also unfair to those losing. They deserve a fair chance to win back what they lost before the game ends.