I know I've purchased Huli Huli sauce here in the Southland, but I'm trying to remember where exactly. It could have been at HOWS market (Pasadena), or possibly a Gelson's or Pavilions. They might also have it at 99 Ranch. In any event, if you don't find Huli Huli, look for a very similar product called Aloha Barbecue Sauce. It's basically the same thing.
If all else fails, there's always the Internet.
re: Jack Flash
I remember seeing it at Bristol Farms in S. Pasadena.
Marukai Market in Little Tokyo (in Weller Court) definitely has it in the Hawaiian food section.
The Huli Huli sauce you're referring to is the #1 commercial brand available. The 3 ingredients are soy sauce, sugar and ginger.
Huli huli sauce is basically a marinade with recipes as varied as your imagination and
taste with the basic ingredient being soy sauce. Google "huli huli sauce recipes" for a start.