Not an expert on the issue, but have had some experience with it with my boys. Just like finding boots for myself, it came down to trying on a ton of boots. I would suggest making a list of what you are looking for- rubber rand, goretex, waterproof, synthetic, leather, height of the boot, weight, and insulation are a few of the things to really consider. Of those, waterproof with some insulation are the most important to me. Then order them online, or ship them to a local store, where you can go in and try them on or return them if they don't feel right. Each manufacturer feels different, so I would encourage you to try on a couple different brands. Personally, you can spend a ton on boots, but anything from 200 on up should be of good quality. I hope this helps some.
Cheers- Dave