Out of warranty exchange through Apple will be $199.00.
Other than that, we cannot guess as to how much it will cost to repair your phone because we don't know what's wrong with it. Either exchange it for the $199, or find a repair shop and have them examine your phone and tell you how much it will cost.
Those findings, especially after a drop, NO (home button, charge, connect) are signs that the Flex Cable #4 has simply come loose from the Logic Board. At my Apple Store the Genius will reseat Flex Cable #4 to the Logic Board for free. Make appointment with Genius, ask them to simply reconnect the Cable #4 to the Logic Board.
With iPhone 3GS before opening and during any repair make sure the iPhone is OFF or your risk damaging the LCD Display or the Display Logic Board Controllers.