Its a used Cerro Forge upper branded by Daniel Defense. I suppose the DD branding makes it more valuable to some but its just a Cerro upper. Maybe 1/4 of all uppers are Cerro. $75 or so.
Then again people pay huge premiums for Colt branded lowers whch are nothing to write home about . Ive even been know to pay $200 a pop for FN lowers only to render them unsaleable by SBR'ing them.