From what I read on the interwebs.. it's illegal to sell ES (Engineer Samples or the likes). 2 x Intel Xeon Processor ES E5-2687W Sandy Bridge 3.0/3.1GHz LGA2011 Core i5/i7
Yes it is illegitimate to buy or sell ES CPUs because they remain the property of Intel, but people do it anyway because there's no incentive not to do it. ES CPUs change hands regularly on ebay but never on forums (go figure).
I would love those CPU's but a lot of money for ES chips, problem is there is a demand for them so they will go for good money