The best Sichuan peppercorns I've found are actually available from one of the local markets, though they're also on Amazon. I forget the details on it at the moment. My favorite bean paste is this stuff, though it's maybe not exactly the right kind of thing for this dish? I randomly picked it up from a Japanese market around here and really liked it, though. It's sort of on-and-off Amazon, in my experience, and even when it's available it's often shipping from overseas. I don't know of a more reliable source for it, but i've made sure to keep a stock.

The rice wine... i've tried several different types but have not been satisfied. Recently i got ahold of some Pagoda brand rice wine and i'm actually trying that tonight in a vegetarian modified version of your recipe. I'm hoping it'll work well.