J.P.
My daughter has two sets, one very tiny (doesn't hold an ounce) and the other holds about 2 ounces. They are both porcelain and were gifts from years ago.
The set she used the most is plastic and holds about 4 to 5 ounces. I have not seen any porcelain tea sets in years so maybe check eBay or an antique store.
Here is a cute one and not expensive.
http://www.christianbook.com/butterfly-porcelain-tea/pd/2...