These are fun, and freak my friends out a lot. I got them to use in a film production. Cannot eat or drink with them, or talk properly either. You have to get used to them. My teeth are also too white for them, they are an "off white" colour but against my teeth the fangs look yellow, so I have to use them in dark lighting conditions so they look good. They custom fit to your teeth and are easy to set up.
This is the cheapest place you'll find these, in costume shops they are 10 quid, and on ebay its even more.
They are extremely fun, and they look awsome.