You can try contacting ASUS directly to ask about purchasing the part you need. They rarely provide any support on this forum.
From what I saw on google, ASUS doesn't seem to have any online store where you can order replacement ROG G571 parts.
A few laptop repair businesses offer to replace the motherboard for you but don't seem to sell the replacement part itself.
Prices on ebay are always variable, it's an auction site, lol. Be careful to note the total cost of the purchase, many vendors advertise lower sell price but add the remainder into extravagant hidden shipping costs. And chances are they're basically just trying to make whatever money they can from piecing out salvage from a broken G571 laptop (which might have, say, a smashed screen or dead battery but perfect motherboard).
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