I know I've seen it around, but the selection in Chinatown is quite limited usually - if a store has it, you might find only one brand. And likely it'll be a lower-quality one, Chinese-made.
Considering even small containers of it last FOREVER, it's worth it to go to K-Town to pick it up a proper tub of it, made with sun-dried peppers and minimal other ingredients. Lots of the Chinese ones add corn syrup, aren't fermented, etc. Hahn Ah Reum has a great selection, though it can be confusing with so many brands.