Love the computer system when it eats your post.
When my kids were little and we were living in Canada (Quebec) I would buy coats at the end of season goose down for $10 to $20 for the next season. I would buy two sizes larger than they wore to allow for growth. Also hats and mittens/gloves were needed along with boots. While hubby was active duty we lived in NV, AZ, and NM so the weather here was not as harsh. Even in Europe the weather was not as cold but we did have some cooler winters.
My usual go to stores were Sears and JC Penney and many were from catalogs back in the day. Now I would go to Burlington Coat Factory and look for coats.
Good luck in your search. Go with what your pocket book can afford. I love a few names that are expensive but those coats are still with me as an adult and they are 25 years old (ski jackets).
the other S.
PS At the age of your kids, I would get them involved as they are the ones who are going to wear them. The 15 year old is going to be a challenge because of the peer pressure and the fads. But you should be able to find something. You didn't say if they were boys or girls. That would make a difference.