Mag. Pfft. The only "good" Mag light is the Mag Charger.
Some alternatives:
Pelican M6 Lithium powered light: Kind of like Surefire's lights, but much less expensive. As bright as a 4D Mag, but pocket-sized. Powered by 2 CR123 lithium camera batteries. Batteries last about 45-55 minutes of continuous use before dimming too badly. You need to order the batteries online for $1.00 to $1.25 each though. Those batteries are still $10-12 a pair in stores like Wal-Mart and Best Buy.
Princeton Tec Attitude 3 LED light: A perfect replacement for a mini-mag. Similar light output, but many hours of bright light available from 4 AAA alkalines.
There are many others, such as the CMG Infinity Ultra (1 AA, 1 LED, 11 hour run-time, aluminum body) and the ARC AAA (1 AAA, 1 LED, 5 hour run-time, aluminum body, 1/2 inch shorter than a Mag Solitaire).