The problem is with the request - you can get a great, high-powered light, but it won't run particularly long or be particularly cheap. And a high-speed, self-defense light probably won't see a lot of use around the house because you'll blow through batteries pretty quickly for a limited return on operating life.
The good news - any relatively bright light will mess with an aggressor's night vision, although effectiveness will vary in accordance with the situation.
You can look for some great LED lights with multiple power settings - which allows one tool to be scaled to fit the situation as needed. However, I don't like complicated when a response needs to be fast and done right the first time - like self-defense. It would really suck if I needed my light to be on "high" and I left it on "really low" the night before. Just a personal quirk.
The Surefire is, as always a great choice - the only drawback is the CR123 battery. For those of us who live and breath gadgets and gizmos, we buy CR123s all the time, but otherwise it can be an unusual battery to put hands on in a pinch.
The Inova "Bolt" series is a nice compromise in my opinion - the
3.8 watt Inova Bolt has a nice feel without a hefty price tag, runs on 2 AA batteries and produces a respectable beam. It uses either a momentary flash tailcap "clicky" or a constant on by twisting the tail cap. I carry one as my intermediate working light. The
Inova website has more specs if you're interested.
-Medina