The place is kind of hidden, but it's in the main mall of Chinatown. I think it's called L. L Arts Tea Gallery or something like that.. I'll try confirm for you. It's on the second floor of a building, sort of up from the carpark in the mall, if you know where that is. I think it's just to the left of the 'Green Tea Restaurant' if memory serves. You go up a small flight of stairs and it's there, they also sell lots of art pieces.
I've been there a few times, and talked with the owner quite a lot. Last time I was there he told me he was flying to Yixing that weekend. He told me that he collects teapots and even has some from famous artists. Once you get him talking about tea, he gets quite excited and shows a lot of his teapots. Unfortunately, he doesn't speak terribly great English. But what I gathered from him is that he doesn't order in extremely expensive teapots, because he said that most people don't understand the value and think that he's crazy for selling them at that price. Anyhow, you can go there and order tea and have a chat.. he has many, many books on tea, but they are mostly in chinese..
I'd love to get someone else with a bit more 'tea knowledge' to check it out to see if it's decent or not. If you check it out, let me know what you think =)