lulu dupes off Amazon (they have joggers, leggings, yoga pants, etc). There are several different brands, but some that are good quality are Colorful Koala, **KRZ Yoga, and a few others.
For $20-25 you can get a pair that is very close to, if not the same, quality as the $100 Lululemon joggers/leggings.
With several girls in my house, this tip someone gave me was better than any stock tip I've received in the past year.
**Correct brand is CRZ Yoga (corrected in thread below)