I have plastic file box that I use just for crops and that I NEVER UNPACK.

Inside, I have hanging file folders (8.5 x 11) for each color of paper. Before I go, I look through the files and add colors that think I might need.

I have one extra file at the back of my paper to place newspaper articles or memorabilia in -- keeping it from being bent or wrinkled when I take my suitcase of goodies!

Wal-Mart has plastic folders in their craft section that I slip my 12 x 12 paper in.