http://www.betterviewdesired.com/BirdW.html

That article should help to answer your questions....and a whole lot more.

For the price I think the Bushnell Buckhorns from Cabelas are an excellent $100 and under full sized binocular. If you are looking for something a bit more compact but with very good image quality then the Bushnell Legend 10x26 definitely it worth considering. Price is, again, right around $100 at Cabelas.

Hope this helps.