Jordan--if you are interested in a 20# co2 tank, I have a guy that will be selling me one this weekend for a good price and I know he has more. Most are out of date but it shouldn't be a big problem. He is out in Palmdale area and I'm in West LA, but he is often in downtown LA, which isn't so bad. Let me know if you are interested and I can give you his email.
Also, don't mean to compete with you, but I'm in LA and also looking for similar items. Craigslist is fairly barren these days. I'm especially interested in corny kegs, 6 or 6.5 gal carboys. Also interested in wood barrels, brew stands, pots or keggles with ball valves, cheap kegerator, fridge or freezer, and other random brewing gear.