Some good stores to find sweatpants/athletic pants?

I'm trying to find a good store to find athletic/sweat pants to wear to school and around. I like Nike and Adidas, but they are so expensive. I like the on-up side pants, but where do you find those? The only stores I can think of that sell that stuff are Sports Authority, 's Sporting Goods, and Johnny Macs. Do you know any places where you can get cheaper, nice sweat/althetic pants besides like, Target and Walmart? Any good stores in the malls???