If I were you, I would get a gaiwan, and maybe a nice teacup or two. I wouldn't worry much about the clay of the cup, yixing or not yixing, glass or whatever.
Then, as suggested, I would buy samples. What I liking about tasting teas, is that you are quite largely in control. Try out what you like, brew tea how you like it. So called "gong fu tea ceremony" is fairly loose term, and I bet people here could give you a multitude of definitions. I think the basic idea is to use small brewing vessel, lots of tea compared to water, hot water and take many short brewings out of same leaves. It's not that important how much leaf do you use, or how long steeping times.
About pu'er, I think it's really important to realise that there are many different types of pu'er.
Pu'er can be either ager-young, blended - single estate, big factory - small factory, old tree - plantation bush, sheng (raw/green) - shou (cooked/black)..
It's really important to realise these, and to find out what you prefer. I would try to get as large array of samples as possible, to find out your pu'er taste. Then you can sample more those categories you like, and maybe even buy a cake. Cake is a lot's of tea, I would hurry getting that big amounts to my shelf.
Essence of Tea is an excellent place for getting some fairly cheap yet good samples of aged teas.