I'd imagine the prefab stuff is pretty expensive. We built the window between control room and live room and we're idiots. It wasn't terribly difficult and although the glass was not cheap, the rest didn't cost much at all. We built a window about 5' by 3' and a small maybe 2' by 2' for under $800.
I finally got my Rusty Box today. I only had about twenty minutes to play with it, but it was enough to know that this thing does what it's supposed to do very well. I checked it against my TS-50B and it's pretty awesomely accurate. I had fun feeding it into my TS-50B for extra crazy.
I'm guessing that the overheads are mid/side and they weren't decoded prior to tape, so we're hearing the mid and out of phase side. This is a pretty educational thing to hear and it's a great lesson in getting good sounds to tape. You throw up the faders and it sounds pretty much like the record. I...