First how do you know the Mother board has gone.
I would get a estimate from a reputable local repair shop to supply and fix the board. You would then have a guarantee on the board and work.
Then you can work out if its worth it.
It may be cheaper to buy new and sell yours on ebay for spares and repairs. This way you can recover some money.
If you are certain its the board you could have a go and replace it your self.
There are quite a few sites that show how to go about the replacement and tips on what you should do. see here You would also need the drivers for the board that normally come with the laptop when new on a DVD or CD.