I dunno about SF, but in NYC a lot of the hardware stores carry a "Tuff Stuff" brand heavy chain that's like the big covered Krypto one but 1/3 cheaper. Physically it looks the same (square links, weird multicolored petroleum sheen, nylon cover) and since a lot of this is all about the look of having a massive chain it might be worth checking out. I have no idea what makes it cheaper but it seems pretty tough and hasn't failed me yet, knock on wood.