Question about G500 w only 750 miles

Hey there dudes,

A buddy of mine is looking to sell his 2004 G500 (silver) which has only 751 miles on it literally still has the new car smell (it has done almost nothing but sit in his garage since he bought it), and was offered a trade in value of about $55000, but was told by another dealer that if he sold it himself (perhaps on ebay) he stands to make a good bit more. Do any of you guys have any ideas of what a car in that incredibly like new condition would go for if he sold it himself?

Thanks to anyone who can give me some insight.

for more:

Brand Promo Video