Sometimes you're going out of town and you just need a small part of a storage unit. Do you have to pay for a 5' x 5' room? Not necessarily. Here are some possible solutions when you only need a little storage space.
Try Renting a Mini Storage Unit
Some companies allow you to rent mini storage units that are a fraction of the size of a standard storage unit. These could be a locker, a cubby, or simply a small room. Look in your area to determine the smallest storage units available; you might be surprised. An added benefit of smaller storage units is that they are often near the front of the facility where they are well-guarded by security. Just check the locking requirements for these units and make sure the locks are changed between each rental.
Split a Storage Unit
You could also look into the possibility of sharing a storage unit with another tenant. You might find people who are interested in this arrangement via a classified ad, and their rental fees may cover most of your own. Be sure to get a background check on anyone you agree to give access to your stored belongings; you wouldn't want to find that your stored items are gone when you need them most.
Ask a Friend
Outside of these two options, perhaps you can look into the option of having a friend store your items. This works best when you can come back for them within a reasonable amount of time. Indefinite time periods create a bit of an imposition, since you are taking up a friend or family member's home space and asking them to be liable for your belongings. If you are planning to store your items beyond a few months, finding the appropriate storage solution is a better idea.
Consider a Portable Shed
Sometimes, you can erect a portable shed on your property pretty easily if you simply need additional storage space. These have great locking options and keep your items safe from the elements during the seasons when they aren't in use.
So, the bottom line is that there are plenty of options to consider for storage when you don't have the money to pay for a full storage unit or you simply don't need the space. Start with asking how your storage facility can accommodate you. From there, look to your community for help in making storage units more affordable.