I rented a nearby Kennards storage unit during my last move. I just used a small really basic unit (just an empty room with a locked roller door); and I only used it to store my Transformers toys, so I didn't need anything bigger. Had to also purchase a padlock and key, but that's not expensive. I packed my toys in various cardboard boxes, but with layers of scrunched up paper in between. Bigger and tougher toys at the bottom, smaller and less durable toys at the top.

I had about 1965 Transformers at the time.