Traditionally garages were built to park our vehicles out of the hot sun and weather. Many people convert their garage into a workshop, while some want a place to keep things because there's no more room in the house.
If you want to buy prefab garage kits, you can browse http://www.whiterosebuildings.co.uk/prefabricated-garages.
There are companies that their only business is to organize your garage and/or closet space. They have prefabricated storage shelves and cabinets that get every single item off the floor and into their proper place. Even bicycles, tennis rackets, bats and gloves will have their rightful home.
You do not need to spend hundreds to get the storage components assembled. Sit down and draw out a blueprint which you may follow, and begin easy.
The first thing you need to do is to check your local zoning laws to ensure your land meets these requirements. There shouldn't be any restrictions about size or building materials. You also need to acquire a building permit, even if you are assembling a prebuilt unit.
Once you have decided on the size, start preparing the site where your structure will be located. A foundation is very important, and you need a solid plan from the manufacturers. These plans will give you the exact dimensions. Once the prebuilt garage is attached to the foundation, your structure will be stable and durable.