You craft them from tinker tool and the treasure hunter map from carp tool. Bod and power scrolls are in scribe's tool. You can see what it takes to make each individual key. They are not easy items to get...... but then again they are made that way. It is possible. People have made all the keys. Another one of those things that require you to put in the time and effort.
You could buy them. I don't know anyone selling right now.
As of 04-29-13, the Grocery Basket Key is not available to craft It has been given out once as an event reward, and was available via the 5th Anniversary Cake. At some future point, we may make it available in other ways.