I have a Pat Marlins Gas Check Maker in 22 caliber and I need a pistol brace, buffer, buffer tube, spring, castle nut and end plate for an AR.
(no ejector arm, by the way. A separate $5 item from PatMarlins, I used an Allen wrench laid in my Rock Chucker)
The AR parts come in at less than the gas check maker (and the GC maker has a 90 day wait) so it's a pretty good deal for someone.
I'd also consider 2 mil-spec lower parts kits (which is a closer to even trade, I think) if the brace, etc can't be found in a few days.
Everyone pays their own freight.