[1up5dwn]

Does it HAVE to be a cargo box, or would you settle for mesh material? I'm pretty sure it'll be cheaper. Just make sure it's waterproof. Probably easier to store also. They're reasonably priced. Just look around.

http://www.roofbag.com/?CPID=1100&kw=car+top+carrier+EXACT&gclid=CMzwzLudhLcCFUWK4AodHxcA7Q