Sheung Yu tea shop on Temple Street in Kowloon initially looks like it might be a tourist trap, located as it is at the entrance to the Temple Street Night Market. However, it's owned by the founder of the Sheung Yu Tea House, who helped establish the Flagstaff House Museum of Teaware in Hong Kong Park.
There's a wide selection of Yixing teapots at different price points, gaiwans, and other teaware. The lady who runs it is friendly, helpful, and speaks good English, and there is no pressure to buy. They sell tea, too, of course, though by the time I found this shop I had enough tea and was looking for something to drink it from. I bought a Yixing teapot, pictured.