I spent a good while looking for one myself,
and ended me with the general acceptance that if i wanted to do it really well,
id have to make my own lifecast and make my own mask to fit me.
If you have the time, theres loads of tutorials on teh net about how to do it.
Another downer i found out was that they actully digitally reduce the nose in the movies, so if you're going for it, hope you have a small nose!!