Screen wont work but computer will?

I recently spilled a small amount of water on my macbook pro and now the screen doesnt work. The computer starts up and makes sound so I took it into an apple store. They told me there was water damage and the logic board was broke so it would be 600 to fix it. I couldnt believe it. I plugged my computer into a tv threw the mini display port and everything works fine. My question is does the logic board really need replaced? Where can I get this fixed the cheapest or should I just sell it for parts? If so where and how much should I look to get? Any help or suggestions would be greatly appreciated. Thanks.