I bought mine off ebay for £800 which sounds a lot but when you consider that it is a $7000 machine that's not bad. Just googled it and you can pick one up for £550 on ebay or £5781 (+vat) on another site. It's a Precor C964i like the one in the picture but with side rails as well. Unfortunately I don't have all that space in the picture. It's in the already crowded garage which is now waist deep in boxes of stuff from Vicky's flat. Good job I'm not claustrophobic. It's the only treadmill I've seen that declines (3%) as well as inclines (15%). Being a big heavy commercial machine it's got a good shock absorbing running bed and is as solid as a rock to run on.
As implied above I use it as a task master. It shows no mercy except on the heart rate control setting when it will reduce the incline if your heart rate is too high (it'll also raise the incline if it's too low). I also use it to experiment with techniques: stride length, running style, breathing patterns etc.
I went on it tonight to do some interval training (5 x (3mins @ 6 mph + 3 mins @ 10mph)). I had to grit my teeth a bit for the last one but made it.
Not as fast as I was 10 years ago (not yet anyway!).