How much does it cost to replace a battery and get a new frame for a computer?

Okay, I've had this computer for around 2 years, the frame {you know, the stuff around the screen and keyboard} is damn near destroyed, and the battery is so bad it can only hold a 15 minute charge. I use a Dell Windows 7 computer, it was around 1,000 dollars. In all seriousness, how much would it cost to replace these things? 100$? 500$? Or can you not replace them? Also, I wouldn't mind also knowing how much it costs to replace a screen, because the screen also has water damage...