The Longjing rule simply stated: Do not go to Hangzhou to buy Longjing – the best has already left town.
I think this is a basic rule not only for Longjing, but applies generally to all teas and teawares. The best of the bunch leave very quickly, and go to where the market is. When I have friends who go to Hangzhou and buy Longjing, they inevitably end up with some mediocre stuff priced like premium tea. The same can be said for Wuyi yancha, where shuixians are sold for dahongpao prices (with nice boxes, of course). Friends who visited Yunnan tea mountains in hopes of finding that awesome treasure usually come back with plantation teas that are very mediocre, without needing the plane ticket and all the hassle. In sum, don’t go to the producing region to buy what you’re looking for. Go to big city markets instead.
This is really simple economics – richer cities can afford luxury goods like top flight Longjing or spring old tree Laobanzhang (regardless of what you think of them). These teas are expensive, and not many people can afford them. The farmer has two choices – sell it to the middleman whom they deal with regularly and trust, and get a good price, or produce it and keep it and hope they can sell it to some tourist walking by for a better price. What would you do if you were the farmer?
Instead, what’s kept for the tourist trade (and this includes many occasional tea merchants who think they’re sourcing it from the real deal) is usually the B grade stuff. Tourists, and occasional tea merchants, go to these places looking for good tea. Among the ones they sample, what they’re buying may indeed be the best of the bunch, but what’s missing, of course, is the stuff that never made it to their mouth – stuff that was locked up months in advance by those with the necessary local connections.
So, in sum, follow the Longjing rule, and don’t go to the producing regions and buy tea. If you want greens, go to Shanghai. Kunming is probably not a bad place to start for puerh, although a lot of the best stuff get dispersed to other major cities too. For oolongs of various types, Fuzhou, Xiamen, Hong Kong, and Taipei are good places to shop, depending on the style and type you like. One of the best places I’ve found for Wuyi yancha was in Taipei, a guy who sold me some incredibly expensive but awesome tasting rougui. It’s not a coincidence.