I've never bought a treadmill myself, because I run outside more often. That said, the one piece of advice I've heard is not to buy a refurbished treadmill. That isn't to say you shouldn't get a used treadmill, if you are confident that the person who owned it before never used it. But don't get one from one of those companies that buys out the inventory after it's been used for a while by a globo-gym or fitness center, then fixes it up and resales it (in Utah one of the bigger companies that does this is Shape Up Outlets). It would be the equivalent of getting a branded title car and not being able to have a solid report on what salvage needed to be done and not being able to have a mechanic check the car out before purchase.

They may offer warranties, and I'm sure that you know they do a statistical analysis so that the warranty ends soon before the machine dies, but the warranty equation is also skewed because they know that a large portion (if not the large majority) of purchasers won't use the machine with regularity.

I knew a guy who worked for Shape Up Outlets and he recommended that I not buy a machine from them.

Also, don't get an elliptical.