If you are new to fitness and exercise, if you are overweight, if you are older, or if you have weak joints, chronic pain, or other injuries, then you probably want to find a machine that's affordable, comfortable to use, and easy to work with. Elliptical trainers can meet all of those criteria, and help you lose weight, tone your muscles, and get into better shape. But elliptical trainers can also be very expensive, because they are relatively new to the market, and they come in different categories with different available features. You want to spend a reasonable amount of money to get the exercise machine that you need and want, but you don't want to be overcharged, or worse, pay too little and ultimately be disappointed in your machine.
First, sort out your budget. If you could never afford an elliptical trainer over two thousand dollars, then you don't even want to consider them when you do your shopping. The second thing to consider is if you have ever used an elliptical trainer before. Some people purchase their trainers based on the idea of the trainer and the promises certain advertisements make. If you are going to be a more casual user, it doesn't make sense to start with a machine designed for an athlete in training. If you've never used one at all, it doesn't make sense to invest in a very expensive machine you might not even like. Finally, determine in advance what sort of features you are looking for. If you know exactly what you want to buy, you can't be manipulated into buying a machine that offers something you don't need and has a higher price tag.
Once you've considered those areas, you can set your elliptical trainer budget and find a machine within your pre-determined parameters.