Can you find out where the off brands are made. Most times that will give you an indication of the quality.

Here is one review that can get you going. I too haven't heard of some of the brands listed.
http://www.opticsden.com/best-binocu...FUg8gQod6dwPnw

This site will give you an idea on what type of quality to expect in your price range.
Expensive vs Cheap Binoculars - Best Binocular Reviews

Good luck, its a huge market. I have a set I got for a 5 year work anniversary that I keep in my boat. They are in the low cost category. Functional, however there are times When I wish I had better quality.