Back - Alpha434 will make inception barrel backs for $75 with a miniumu order of 10 pieces - See this post
.680 and .682 Stainless steel by RedneckSniper - See this post
.670, .678 and .685 Brass by TyMcNeer - See this post
(I will ball park my price at $45 each, though I reserve the right to change that based on how much extra time it takes to get the inserts right.)
I would be willing to generate a spacer to allow the use of "normal" Freak inserts in the 9" Inception back.
That pretty much sums up the status of the project.