It’s somewhat ironic that while knowledge and appreciation of non-Cantonese Chinese cuisines have increased in Chinatown over the past quarter century, availability of non-Cantonese staples has diminished. Twenty-five years ago there was an outlet of China National Native Produce and Animal By-products Import and Export Corporation on Broadway (and yes, the whole name was on the facade). It was a convenient place to find staples like Sichuan peppercorn. Across the street was a market, Metro Foods, which specialized in Shanghainese products, not only those with long shelf life, but also frozen mud-skipper eel, yellow croaker, beltfish and the like We met a young Shanghainese couple there who periodically drove down from Portland to stock up with goods from Metro. THe largest market in Chinatown then was May Wah, which was a convenient source for regional Chinese products before it pulled up stakes and moved to the Richmond.
When it comes to Sichuan peppercorns, I think some of the Stockton St. merchants got burned for having peppercorns in stock during the import ban (some without even realizing the ban had been put in place) and will have nothing to do with them.