Made of cork, made to party!
See comment above for pony and you can make your own cannon out of a wine bottle cork. Just carve it out, cut off some wheels, and paint. Tah dah!
Where was this obtained, and for how much might I purchase one?
I got mine in a set with Celestia, Twilight, Apple Jack, and Spike at Target but I know they sell them at Toys R Us too.
Hmm, Pinkie Pie + party cannon = RUN FOR YOUR LIFE!