Here's what pricecharting says (not perfect info but usually a decent starting point)
imageIf you are buying it with the intent to flip for profit, this would suggest that there isn't any to be made at that price.
If you have extreme nostalgia for n64 and want something like this as a showpiece for your collection, then only you can decide if it's worth it to you. At the very least it doesn't seem too off the mark, but if it's a private sale and he isn't paying eBay fees or anything you should definitely get him to knock some $ off.
(If he sold it on eBay at that price he'd pay about $230 in fees, plus he would have to deal with shipping and possible scam buyers etc.)