Cargo box for roof of car

luvmytab

Anyone have suggestions for a cargo box to put on top of my toyota forerunner? I have the roof rack. Looked at Thule and Yakima and they are soooooo pricey!!! I want to put lots of extras as I often have 3 kids and a dog in the way back and it gets super crowded. Anyone suggest something not as pricey?

Marceline

Some ideas: 
Keep an eye on Craigslist for people selling used boxes.
A cargo basket & cargo net instead of a box.
A car top soft storage bag instead of a box