The linked auction is from "cellphoneforever". If you look at the feedback from them, you will note several people complaining that their "new" phone was actually a refurb or previously owned device. In particular there are at least 5 reviews from N900 sales, and all but 1 notes that the device was clearly not "new". In short, there are plenty of unreputable dealers out there that will slap a "new" label on just about anything to sell it.

N900 production stopped some time ago. If there are still new-in-box devices, they're not common, and probably in shops that have them overpriced for their market (eg list price + markup still).

Noting that there are other used devices out there for less is fine. Calling someone names and insulting them isn't. Especially when you don't bother to check your own "facts" about "new" devices being available.