I had been an avid fan of the coconut milk mentioned in the link, but I've decided that I'd like to go with one without preservatives. I recently purchased Thai Kitchen brand at whole foods and I think it actually has a cleaner taste, the other seems to have a slight sourness/metallic taste. You can also look in the frozen section of asian markets to get frozen coconut cream/milk. I've never tried though, seems more like a hassle than pulling out the can opener.
Here's a link to Thai cooking teacher, Kasma's recommended brands.
I haven't been there, but Battambang Market might be a good place to call. Here's more information -
It's not something I've seen in Chinatown, not that I've been looking. Ranch 99 in Daly City would have coconut milk. New May Wah on Clement would be another spot.