I have a stack of old suitcases that I found here and there in antique stores and flea markets. Most of them are on the small side, but that's good! I keep my print books and all my book signing paraphrenalia in them. They're roomy and dry, and being small means they're not that heavy to carry. Plus they stack well.
This way when I need to pack up to go to a book signing, I have everything all "packed" and ready to go!