My mom simply refused to buy us expensive clothes. She would buy clothes extra big so we could wear them longer and we would go to school with the waists cinched up like paper bags and jeans cuffed when it wasn't the cool thing to do. And my poor sister got stuck with hand-me-downs that I wore five years earlier, and were always completely out of style by the time she fit into them. We looked pretty bad the whole time through school.
I got my first pair of Guess jeans when I started waitressing at 16. From that point forward, I pretty much bought all my and my sister's clothing ... Mom stopped buying clothes completely. Sis was 5'9 at 13 and only slightly slimmer than I was (we were often mistaken for twins), so we shared all my clothes. And I didn't mind either because otherwise she didn't have anything to wear and I had great empathy there. The only problem was that colored jeans faded fast and slouchy socks stretched out when worn twice as often by two teenage girls!
I don't want to follow in my mother's footsteps, but gosh it is expensive buying a whole new set of clothes & shoes each season for a girl and a boy. Mine are growing so fast, that a pair of jeans may be too short within a couple months.