Teenagers and frugality don't exactly go hand in hand. Teenagers always seem to want the latest and the greatest regardless of cost. I have found that teenagers are much more expensive than younger children --- even though I had to pay the cost of daycare back then. However, you CAN get the thinking along the right lines --- it just takes some modeling of behavior and a willingness to say "no".
When Princess Penelope and I went back to school shopping for clothes, I told her what my budget was for what we were shopping for. Knowing that there was a limited amount to spend, she went straight to the clearance racks and started diving in. It was interesting to watch her pull something off the rack, admire it, look at the price tag, do the extra percentage math in her head, and put it back on the rack if that item was going to eat up too much of her clothing budget or toss it over her arm if she wanted to try it on. I asked her why she put something back and she said "That will eat up half my budget, I don't want to try it on, love it and then be completely limited on what else I can get." Is it weird that I was proud?
Tuesday, she needed to go to Target to get new headphones for her iPod, she wanted to go there specifically because she had a gift card from her birthday. I had also wanted to go to check out the back to school deals, but time hadn't allowed. Before she headed out, I flipped through the Target ad, but wasn't overly impressed.
I then made a quick list of things she needed to check the prices on for me and handed her a Target gift card with about $15 on it to pick up those items if they were a really good deal (because I didn't see them advertised). She called me when she got there and filler paper was a better deal there than the advertised price at Walgreen's --- so I had her pick up 6 packs. She called again to ask if she could pick up the same type binders she had gotten last year because they were on sale for much less than we paid last year, I gave her the go ahead because those had actually lasted the entire school year. She picked up the items we discussed and came home with $1.21 left on my gift card.
Last she went to the back to school/dorm area and took pictures of things she wanted for when she goes off to school next year. Her idea was for us to go back in a few weeks when some of that stuff is marked down and get some of that in advance. Not a bad idea. Especially when I know these are things that will be needed!
It can be tempting to give your child everything they want when they want it. But if they know how you shop and what you are willing to pay, it can make things a lot easier. Letting them sometimes make the choice about whether or not something is worth the cost WILL pay off in the future as they start to understand the relationship between money and what it takes to get it and what it buys.