I plan to start riding to school (classes 2x week). On the way home I want to do some grocery shopping. Do you gals have suggestions about baskets/ panniers? I think I could just strap a milk crate on the rack and fit a couple bags in there but my center of gravity would go up. I don't want to spend a fortune on big panniers. Someone here said her groceries fell out of the Nashbar bags. What works for you girls?