Honestly, I think this guy is pulling your leg. Like the other guy mentioned, if no one has heard of the morph than it's probably not legit. I personally have never heard of it. To me it looks BCC and remind me alot of one of my boas. My best guess is he/she is some kind of cross. I provided a pic of one of my boas that I feel shares some resemblance in the patterns and from the looks of the tail, I can see some costa rican influence.
http://s865.photobucket.com/albums/ab215/Jeremycl82/?action=view¤t=001-6.jpg
my guy is a columbian hypo and costa rican cross. Nothing special, but looks different much like this one this guy is offering you. I would say for the price he wants you can get a really legit boa morph from a legit breeder and not have any worries, or you could buy his boa that no one really knows anything about and end up getting screwed...just sayin