My personal take on glass...
1. Buy the absolute best glass you can afford. Cheap or low quality glass is worse than no glass at all. The image clarity--particularly around the edge of the lenses--is crappy on cheap binos and it WILL fatigue your eyes to use it. Because it makes your eyes tired and sore you will not use it much or at all. Which means you have a really expensive neck weight you are lugging around he woods instead of a cheap, marginal, pair of binos.
In comparison, a good pair of binos will produce clear images all the way out to the edge of the lenses. This make it easy for your eyes to use. and because of this you will enjoy them AND use them more. Which is the whole point of this exercise ladies and gents. Your binos are your X-ray vision and only work if you uses them more than not.
The next time you go to a sporting goods counter try several pairs on binos and don't look through the middle of the lens. Even cheapos are clear in the middle. Make a conscious effort to look through each lens separately and look around the edges at something with a straight line about 50-100 yards away... You will literally see why the expensive glass costs what it does. In the blind your eyes will feel the difference and fatique less.
In the eastern US most any bino over 8X is too much magnification. 7 or 8X is far more useful in the hardwood forests. First, its easier to get on a moving animal with lower magnification. But more significantly is the lower power will have a far superior depth of field--the clarity of the image will extend farther into the clutter of leaves and trees! This is what you want when you are trying to pick out a few hairs, or a flick of a tail, or an eye among the branches and leaves. If you doubt this sometime take a 4x rifle scope and look into the woods and take a 12X scope and look into the woods. Notice how the 4X can see with greater clarity deeper into the woods! Again...that's what you need in the woods...not more magnification.
Out west its a different ballgame and a pair of 10x Binos is what you want.
That's my take. I'm far from a rich man but I bit the bullet and bought a pair of Swarovskis a decade ago. If I lost them tomorrow I'd buy another pair before the week was out...in a heartbeat!