The first web search returned the Spirit XE350 elliptical trainer as a best buy. I like the heart rate monitor and the upper body workout features.
Found a discount house called Fitness Blowout that says they have some great prices. Make sure to mention Your coupon code is: F999 for a bonus warranty upgrade.
Treadmill Central has a nice manufacturer/model comparison tool.
Researchers at the University of Wisconsin, compared the NordicTrack Ellipse elliptical trainer against a motorized treadmill, a stairstepper, and a cycle ergometer. The study revealed no significant difference in oxygen consumption, heart rate, and calorie expenditure between treadmill running and the Ellipse. Both the treadmill and Ellipse provided the test subjects with a superior workout over the stairstepper and cycle ergometer. John Porcari explains, "Since the ground reaction forces on the Ellipse were less than half of those during treadmill running, this type of motion may provide a workout similar in intensity [ed. to treadmill running], but with less chance for orthopedic injury [ed. low impact]."