A Surefire G2 LED makes a decent handheld and can also be put on an AR-15 with a 1" mounting ring, of which many are available. Together that would be less than $100. You can also get a corded pressure plate that replaces the push-button end cap for about $30.
I don't really put much stock in the whole "blind the BG with the brightness" idea. I generally carry a Streamlight PT1AA. It's 50 lumens at it's brightest, and also has a low power, and a strobe setting. I like it because it takes 1 AA battery, is small and light, and cheap enough that I can get a couple of them and stash them in my BOB, glovebox, night-stand, etc.
I also carry a 5.11 "Light for Life" on duty which has a 270 lumen peak setting, is super lightweight, and recharges completely from empty in about a minute. It can also be charged 50,000 times before losing it's ability to store power. Meaning, you could charge it once a day for your whole life and never wear it out, hence the name. It's one of the best lights I've ever owned.
On a side note, I think it would be awesome if 5.11 would make another "light for life" but about the same size as a G2. I think there would be a tremendous market for a small handheld tac light that recharges in less than a minute and lasts a lifetime. No more 123 batteries.
EDIT: I just checked out the 5.11 site and saw their ATAC A1 which seems to perform the same function as the PT1AA, but with twice the output. I may look into that...