Please have a search on this forum. NO ONE will recommend you buying one of these "new" devices. Whilst it is remotely possible that there are some old stocks found fallen behind a shelf in a warehouse for 5 years, it is more likely that these "new" units are in fact "refurbished". Often in a rather sorry condition. Unless you know exactly who you are buying from and the whole history of how this "new" device stayed in the box until now, I strongly recommend buying one that the seller honestly offesrs as "used" and describes what condition it is in. Look in Buy And Sell on this forum, I believe there is at least one on offer right now.

As far as the price is concerned, a (used, obviously) fully working N900 in a good cosmetic condition, with a box and all original accessories is IMO worth about 70 GBP (or equivalent) plus postage.