Do you mean an elliptical machine? Don't buy anything you haven't ridden first.
The ergonomics tends to be crummy even in gym-caliber machines. The foot pads are splayed wide apart, and the size of the stride circle is way too big for shorter people.
If you can find one that fits, then look for the same things you'd be interested in with any home exercise machine - is it flimsy? is it so loud you wouldn't be able to deal with it for the duration of a workout? How easy is it to change resistance during a workout?
But I'd look at fit first, and I wouldn't honestly be optimistic about finding one, especially with the issues you've had.