Cheapest Storage options

HI I am moving into a smaller house, and I have bunch of boxes that are not going to fit in a small place, So I was looking for long term storage options. Unfortunately places like sentinel and others are crazy expensive. I plan to have this for several years. Anyone know of any really cheap rentals? I am not going to access this often, Just a lot of things I have collected and from my childhood that I really don't want to part with. Looking for any suggestions.