Hi - I just discovered this thread, did not realize you'd posted it earlier.
I really like Red Circle Tea. I think Carnie and Sina are innovative, very knowledgeable and have some great teas. I enjoy their tastings.
They don't have a storefront, but hold tastings once a month. Usually their tastings have been in an art gallery. This month it will be in a relatively new restaurant in San Francisco called Modern Tea (they did another special event there a few months ago together with the owner, I think).
Here's their website:
They make trips for buying and visit the tea farms themselves - they have a lot of knowledge about teas at many different levels, including experience having worked for large tea companies.
I highly recommend going to their tastings; they carry some rare teas you don't necessarily find elsewhere. Last time I went I tried an unbelievably delicious bao chong that just knocked my socks off. It was a competition winner... and priced like it. But I paid for that because it was worth it. And if you like puerh you must try the samples they bring (including some of their personal stuff).
Highly recommended. Have fun!