If you are just training and want to know what you way for your own sake, I would just get any scale and try to weigh yourself every morning after using the bathroom and before eating breakfast. You will establish a baseline and you will know that if you are 2 or 3 pounds lighter you are a little dehydrated.
If you actually need to weigh in for something, get a more expensive scale and make sure that you take it to a place that has an "official" scale so you can either adjust your scale to make it match or you could just know that your scale is a pound or something over the official scale.