I both love and hate buying tea in person. I love the experience of sampling different teas that a shop has to offer. I hate it when I go through all the stuff in a store to find nothing I like (or the stuff I like is too expensive) and have to buy a little bit to save face. Maybe it's just me, but I don't have the gumption to leave after trying a bunch of different teas. Buying tea isn't like buying clothes, where you can window shop and it's pretty obvious what's what. There's only so much that physical appearances can tell you, but that's mostly helpful for pu-erh. Buying tea is like buying cheese or cured meats.You sample some, and than you buy what you like. Maybe this explains why I have a love/hate relationship with buying from the cheesemonger.
I try my best to first assess a tea with all my eyes and nose. I also ask questions to figure out the tea's history. For example, I'm on the prowl for slightly re-roasted or un-roasted aged oolongs. So much "aged" oolong is stuff that's roasted to a cinder and all you can taste in charcoal...no thanks. A heavy charcoal/high fire smell is a deal breaker. For some, a sour smell in the dry leaf can also be a deal breaker. Not so much for me. I relish funky flavors and smells, and I asked for tea that "smells like it had been stored in a cabinet in an attic and forgotten about." I didn't know how to express that "flavor/smell" in Chinese so I used a small anecdote. Ask questions! Did you store this tea yourself? Do you re-roast it? If so, how often? How do you re-roast it? Etc. MarshalN has an entry on evaluating aged oolongs...I pored over it and every one of his entries on the subject. Very good stuff.
Okay, so you've decided on something to try. Now comes the tricky part, because there might be a bunch of second-guessing and confused palettes. I'm not as advanced as many people, so I can only handle at most four or five different teas before my tongue gets confused. Usually the first tea isn't up to par, but it usually gets better when you help the shop keeper hone in on your taste. Sometimes they'll sell some "bogus" information that goes along with the tea...don't buy it. Just rely on yourself to do the deciding.
So congratulations! You found a tea that you liked. Suddenly a tea tasting turns into a poker game, and if you reveal your hand you might be screwed. "How do you like this tea," says the shop keeper. "Eh, it's okay," I say. Unlike with other stuff I don't have much experience with the art of bargaining with tea. I think discounts start when you buy a kilo or more at a time. Also, it helps if you're a return ing customer. Right now I'm "working" this shop. I started off buying a kilo of okay but super cheap "aged" Dong Ding. The second time I went I got a small discount, and hopefully the next I go it'll be a little better. But for people in the know, how much of a discount is there and at what quantity? Is there a difference in discounting for different tea types?
PS: I don't know if this works or not, but I play the "poor student" card. Even if I had a successful job I'll keep talking about the crappy economy in the states. I was able to secure a small discount (on a pot though) with this strategy.