How much would Home Depot be to buy?

The total value of Home Depot's stock is approximately 1.69 billion US Dollars. However, you do not need to buy all stock to be said to "own" a company. Buying one share - as of May 13, 2010, a little under $36 - would qualify you as an owner.

To have substantive input, you would want to be an "insider", which is to say you'd want to own 5% or more of the shares, which would cost you $80,000,000.

To have control, you'd need to either persuade 51% of a variety of the Insitutional, Mutual and Individual owners to vote your way, or simply buy 51% of the shares, which would cost you $816,000,000.

So, $36 to own, $80,000,000 to have a say, and $816,000,000 to have control.