I bought it off LBJArm..
IIRC, he said it was a 300 issue print run given out to people who purchased memberships for Marvel Digital Comics.
I bought it from him raw for $70(??). No idea if it'll ever really be worth that, but for me it was more just about having one of the rarest MK books there is...
Here's hoping none (or very very few) of those other 300 copies are in as decent of shape or ever slabbed. I assume Marvel just mailed them out so most are likely destroyed by the USPS; creases, etc...
I'm not a moon knight fan but reading your post, you got a great buy. Only a run of 300 and you got a 9.8 is definitely a book to have in your collection. Paying $70.00 for is a good price because you got a 9.8 cgc out of it.