Just do it... Don't go cheap or it'll be easy to put in a corner. Don't get one that folds up, or it'll go in a corner. Don't get a fan on it, what's the point, you're there to sweat... Get a large-screen TV to mount on the wall in front of the gem - if you don't the boredom might force you to put it in the corner... I think the wider belt is worth the coin, when you start running on the TM, you'll find the TV sometimes has you drift (like vertigo)..
Don't worry too much about cost... If you're going to use it, use it, a $400 difference over the life of the unit is pennies a day. And a bad TM will make you want to put it in the corner - and that's a waste of all money spent!
And do the GD maintenance! Pay for it or do it yourself... It's worth it!