Here's my 2 cents: What are you are going to do on it? Like JCM, I purchased an expensive treadmill 4 years ago ($2500). It is a Landiscor but fits the needs of both my husband and me. I needed something sturdy enough to handle running for both of us. Mine has a steel frame, 15% grade capability, 5 programs, and I believe a 9 HP motor. Had this only been for me I would have not needed so much power as I only weigh 110 lbs and could have bought a lesser treadmill, but it also had to be able to handle a 225 lb man who runs. As it is, the Landiscor is perfect for us and we both still use it regularly - and we use all the programs.
So you also need to consider if you're walking, running, or both and are you the only person using it, do you want computerized preset programs, what's important to you?
Also, I do recommend the Landiscor...have had zero problems.