There is actually an exercise equipment area here:
http://www.3fatchicks.com/forum/forumdisplay.php?f=213
There are a few threads about treadmills
I looked at consumer reports but unfortunately, the lowest price recommendation that they had was still above $1000.
Here is some info they have on choosing though...
HOW TO CHOOSE
First decide whether you want to devote the money and space to a big exercise machine. A living-room workout is the height of convenience, but of course, you can get fit exercising outdoors or at a gym. If you decide to buy a treadmill, consider these tips:
Try it out first. Every model is a little different, so you shouldn't buy one before using it in the store.
Decide which features you'll use. Some, such as exercise programs, can make a workout more varied and less boring, which may get you on the machine more often. But don't pay for frills you don't care about.
Consider your space. Nonfolding treadmills take up as much floor space as a couch. If your workout room does double duty, a folding treadmill can save you about 6 square feet.
Consider your workout intensity. If you'll usually walk rather than run, any of the tested models will suffice. Decide based on your budget and the features you want. If you run, construction quality is paramount.