I saw your post on the other board and tried to respond but was on my phone and things were screwing up.
You might be interested in this post on the health and fitness board:
http://community.thenest.com/cs/ks/forums/thread/49142504.aspx
Are you looking to just walk, or do you want to run? I got the NordicTrack C900 for $939 on their web site, free shipping (but delivered by a freight truck to outside your door and the thing was HUGE and heavy). There was a $60 off code at the time that I bought it, I found it through a google search.
I want to run and I need length, so I was looking at treadmills with a 60" belt, and this was my cheapest good option. I looked at craigslist but #1 didn't see anything I liked and #2 wasn't sure how to know what kind of condition the machine was in. But if you can find the right thing on there, it would be well worth the money.
I tried treadmills out in the store and I'm glad I did- I was going to go for a Pro Form but I found I did not like the feel of it at all. And for me it was worth spending a little more money to get something I'll use.
If you want more advice, let me know. I did some amount of research before I bought. You want to look at HP, width of the belt, length of the belt, etc.