the reason why there is little to no information around for the N950 is that it has never been distributed commercially (i.e. sold officially by NOKIA)
it has only been lent to developers (usually for free but under very restrictive terms).

some partner companies that developed or wanted to develop software for N9 also got come devices.
as they are not linked to a particular person, some of those devices are more likely to appear on eBay or the like after such companies may have gone out of business.
the prices are usually very hight (GBP 1500+ achieved at auctions)

long story short: it is very unlikely that you will be able to get one.