I have actually read several books in this field as I am an avid astronomer.
1. Look for the words (fully multi-coated) not fully coated, not multi coated, but both. You'll see in the reflections of the lenses purple and green tinted reflections, white reflections are not good red tint is not good either.
2. Check for good tight fitting focus controls, no slop.
3. look thru the binoculars focused at something distant (preferrably steady on a shelf or something) and back away slowly, check that the black circle that comes in from the edges is perfectly black, and perfectly round. You do not want to see any of the "inside" of the binocular. A sqare shape here is bad also (sign of cheap prisms). Also, during this test check that the focused images don't become separated "double vision" so to speak. The images should stay focused together even as you back away.
4. BAK-4 prisms are the best
5. Make sure the binoculars are comfortable to your eyes, if you wear glasses get 15-20mm eye relief, or adj eye cups
6. Anything over 10 power will require a mount of some sort.
I have found that some $200 leupolds, and several Nikons fit this criteria, and you don't have to spend huge money on a great pair of binos,
good luck.
also, for further info there is a book by Phil Harrington, called "Starware" I think, and is pretty much the bible of binos.