I have teenage kids and when they were young, I decided that they needed to learn how to shop wisely, before they got to an age where they wanted all the cloths they saw their friends wearing at school I think they were both around 7 when I started doing that. Each year, usually before the beginning of school, and spring break, we made a list of things they needed -- shoes, pants, shorts, socks, etc. Then I gave them a budget of how much they had to spend. We talked about what we were going to do in advance -- shop the sale racks, and focus on the list. Then we went shopping. We went to the brand name stores (where they wanted to shop) and well as Walmart and Target (where I wanted to shop) so they could compare how much things cost. It was such a great experience because we always came home with everything they needed, and a few things extra. They figured out quickly that they could buy more if they shopped the sale racks, and bought basics at places like Walmart, Target, outlet malls, and thrift stores. They are still great shoppers, and it's rare that they pay full price for anything that they buy. Now that they are teens, I give them each a certain amount of money for school cloths. Anything extra they have to buy themselves. I have a list of jobs they can do around the house to earn money, and they also come up with creative ideas on their own. My daughter started selling some of her nicer clothing on Ebay, and used the money she made to buy new things. We've also had garage sales, and they can keep the money they earn for that. They've learned work, and recycle which is good.
Another thing we do that's a lot of fun is to have a Cloths Swap Party with friends. Everyone brings cloths in good shape that no longer fit, or that they don't like. We set up a display table, and every goes shopping. We try to make sure to keep it fair so that no one person gets all the good stuff. I did that with moms -- trading cloths, and we also traded our kid clothing too. Now my kids host their own parties with their friends. It's a fun way to get new things without spending a dime.