My wife and I last year (actually it would be X-mas of 2003) bought ourselves a Precor Elliptical machine. It's actually the brand you typically see at all the fitness clubs, and yes, it was close to $3000, and that was on sale!
Now, I'm not saying that you have to have one that costs that much to be effective, but we tried out several brands and found the Precor to be incredibly quiet, stable, and well worth the money. Other eliipticals we tried out including Nordic Trac and Proform (i would definitely recommend AGAINST the Proform, although we have a
recumbent bike from them).
Our ellipticall has a powered ramp that adjusts at the push of a button, along with magnetic resistance, has a
heart rate monitor, and in my opinion is built really solid. Brand new they are insanely expensive, but you might want to check out online and see if you can get a deal on a used one. Sometimes health clubs are looking to sell equipment too at a good price. I'm in Chicago, I got mine from
www.chicagohomefitness.com. They even came over and installed it.
Good luck!