Why do I keep breaking my high E string? It usually happens when I bend the string. I bend it like normal but sometimes it breaks anyway. Not everytime of course.
If this continues it will be expensive for me :P

Strings: 0.009 - 0.042 (different types :P)
Guitar: Strat

Where does the string usually break? At the nut/bridge or at the point of bending?
If it's at the nut or the bridge then it's most likely something sharp there.
Okay, thoroughly examine the bridge where it runs over the saddle, and check to see if there are any signs of wear, or rough edges. If there are then some sandpaper should be able to sort it out.