I got a Yumbox, which is one of those pricey bento boxes (super awesome, by the way). But I also have the Rubbermaid Lunchblox kit, it works good. I wouldn't buy the cheap containers for the dollar store IMO.

my oldest will be starting kindergarten this fall and I have been already packing her food lunch box style so that she is used to serving herself by the time she is in school.