Imagine wearing eyeglasses that do not belong to you. Find out whether the lenses are simply glued in, or whether they are nailed and glued, which is preferable. It is also more expensive. Another expense is lens coating. The rule of thumb is the greater the number of coatings, the more money you will pay.
Coatings reduce glare and cut haze.
The next consideration is what power you may need. A higher-powered binocular is typically more expensive. The first number in a binocular size is the power number. It is usually a 7 or 10. It represents the number of times an object is magnified over a distance of a thousand feet.