How much does a Sony Vaio (VGN-SZ640) laptop motherboard cost?

my video card got messed up and in the repair store they told me i ned to change the whole motherboard, and they said it was going to be at least 400$. I am just curious how much does the motherboard itself cost. thank you|||Even a refurbished motherboard will be around $300 dollars. Plus you'll have to pay someone to install it so you don't screw anything up if your not qualified to install it yourself.