I own a few pieces of equipment now that I am selling since I joined my gym last year. I own a good Image treadmill (was about $1700 new), an old exercise bike and a Total Gym 1000. The treadmills all vary and have lots of different things you can do--mine has many pre-programmed workouts plus I can program my own and one for DH too. It has a great incline and a nice, wide belt so it was very comfortable when I used it.
My bike is older and has the handles that move when you ride it. No bells or whistles really just a basic bike. The total gym was a total waste of money as we never had a good place to use it-probably used it about 20 times altogether so we are putting it in our garage sale this spring.
The ellipticals are great, I use one 3 xs a week and the calorie burn can be pretty high--I use the one at the gym at a low level and burn about 300 calories in 20 minutes. If I was going to buy something for home now I would probably buy one of these.
If you are seriously thinking about buying either a treadmill or elliptical, you need to look around. I always did my research online to see what I could get for my $$$, then headed out to the local stores to see what they carried. I ended up buying my treadmill from a local store that sells to health clubs as I wanted something that would last with a lot of running. The price was higher but came with a good (free) service & maintenance plan.
Best of all, try the equipment out--use the treadmill for 10 or 15 minutes, same thing with the elliptical--you really need to see what you are getting for the $$$.
Just my .02 worth, HTH!