For pu'er, I use both Yixing and gaiwan, and the Yixing makes better tasting tea every time. I primarily use the gaiwan for at-work brewing. For greens, stick with a gaiwan unless you want some cabbage-y tasting tea; Yixings hold too much heat.
You can find cheap Yixing pretty much anywhere, especially if you have a local Chinatown. The quality won't be so hot, but they are generally inexpensive. Most of the internet sources are ridiculously overpriced. I have some pots from In Pursuit of Tea (link here) which I am really happy with, but again, they are overpriced.
You can find cheap Yixing pretty much anywhere, especially if you have a local Chinatown. The quality won't be so hot, but they are generally inexpensive. Most of the internet sources are ridiculously overpriced. I have some pots from In Pursuit of Tea (link here) which I am really happy with, but again, they are overpriced.