Aright, so the shop has finished rebuilding the brake booster. So, 1-day turnaround time for this one.
They said that they changed all the seals and the diaphragm. Likely what happened was that I had a leaky bmc and the brake fluid got in and rekked the brake booster over time. (current bmc is ok, but I did have a leaky one sometime ago). Ah I asked about the old parts, but they were in the trash somewhere and I didn't feel like making them dig through it.
$150 done deal 1yr warranty with receipt. I'll toss this back into the car on Friday and see if it's working properly. So far so good though.
That's the old paper gasket on there. I'll probably cut a new paper gasket using some material I bought from Autozone a few months ago. I don't think it actually holds pressure; probably just helps to keep dirt / fluids from reaching that rubber boot.
So yeah, looks like they even repainted the whole thing, which I didn't expect. But that's pretty sweet, man.