A friend of mine converted some Mag-Lites to LED back when the Luxeon Star emitter was introduced. I bet he could build something really nice in a Survivor forend.
I've got a Dorcy flashlight with a 1W Luxeon in it, the whole thing is a bit larger than a 10ga shell, runs on 3 AAA batteries and is as bright as a tactical light (one of the weaker tactical lights, 45 lumens). I've seen them for $19 at Walmart, and this week there's a 3W version on sale at Sears for a bit more. I've also seen MagLites with 3W Luxeons for about $30, and a kit to convert a regular MagLite to 3W LED for under $20. If I could find suitable optics, it would be nice to stick the 3W MagLite kit in a forend with four Nicad AA batteries. 3W of LED is very bright.
If it's for intermittent use, a cheap way to go would be to get a sealed 6V halogen, like the 5W MR11 in my bike headlight, and stuff five AA batteries in a Survivor forend. The bulb shoudl be under $5, and you can select from a variety of beam widths. (I just did a little internet searching and I'm having trouble finding 6V MR11, they all seem to be 12V. I may wish I'd bought some spares when I bought that bike headlight)