I have several, but I believe I have the dust over and forward assists already installed. Would be either bushmaster or Colt brands. What is a fair price to you for a new upper with parts described installed?
Has something changed? Even good brands haven't been too hard to find new recently.
Now if what you're looking specifically for a Mega Monolithic then those are quite a bit harder to find new. Not sure its possible even. I prefer the Seekins SP3R mono upper in the current crop of available mono uppers because of it's flat bottom. I wish that Apex made a mono upper with their "gator grip" forearms for upper builds that aren't going to slide on a bag.