There are plenty of places to buy ocarinas these days on the internet. Which if you are reading this than you're already there!
Many sites sell Ocarinas, but here are a few reputable sellers to help get you started on your search.
I personally bought mine from the second source down there (Songbird Ocarinas) and it was a great product and process.
- Clazyness Whistleworks: http://clayz.com
- Songbird Ocarinas: http://songbirdocarina.com
- Hind Ocarinas: http://hindocarina.com
- The Whistleworks: http://whistleworks.com