I've had a low-end model (1500) for several years - bought it used for $150; it's about $400 new. I love it. I had to replace the cable a few months ago after it snapped, but I found the exact cable (1/4") at a local Farm and Fleet store (most good hardware stores will probably have it as well) - total cost was about $4 for the cable and a couple of metal sleaves for the cable to be threaded around.
You won't get the kind of aerobic workout (slow twitch muscle) that you would with a treadmill or bike, but you'll work the large muscle groups well (fast twitch). It's the slow twitch muscle that burns the most calories, and that's done primarily through endurance conditioning. Total Gym is great for getting a full range of motion in your workout and building strength, stretching for warm ups and cool downs, and keeping the muscles limber.
Can you use an upright exercise bike? I have one of those and I really like it ($129 at Shopko). That combined with the Total Gym makes for a great workout. I've been using that workout to prepare for my 5 day 300 mile bike ride in July. If biking can't be done I'd look into something like swimming for your aerobic work.