How much!!?

Holy %#*&! Stuff starts getting expensive quickly! But knowing what to do and knowing when to call for help are both equally valuable skills. As a general rule if you can screw it up and haven't it's because you haven't tried hard enough yet. Another good rule is if it needs to be done now and done right consider hiring a pro. There is a big difference between living with a bad paint job till next weekend and trying to keep your ceiling from caving in becaused of a botched patch