How to make a 1000 S.F. dry, secured storage space at the backyard w/o building a expensive garage or shed?

I need to store some merchandise at our backyard so I can access occasionally. It's too expensive to hire a contractor to build a garage, because I have a baby to take care of so it's not convenient if they are in a commercial storage place. I used to purcahse a tent and build it but it's not safe at all. Is there any other way to get my stuffs store safely in my backyard? I really appreciate your advise.

Thank you for all your advises. I really appreciate that. Yes. 1000 S.F. probably too big. 20x20 might be OK. I was thinking about use awning. Like products shown on http://www.sunsetter.com. Will that be easier to set up and tear down when don't need it.

not knowing the climate you live in its hard to say but i would suggest trying to locate old pallets from a shipping yard like a brick or lumber is shipped on double stack them keep stuff up off ground and cove with a tarp and tie it down if you are near a marina there is a shrink wrap that can be applied over the tarp to secure it even better most marina have it where else to find it i dont know

There are prefab steel buildings available, but you would probably have to hire someone to put it together for you.

If you have a Lowe's, Home Depot or other lumberyard in your area, they carry a line of sheds in wood, vinyl, etc. and offer assembly on-site. Some will even deliver and place a pre-assembled unit. Depending where you're located, you might have a woodworker that makes and delivers sheds pretty inexpensively. 1000 s.f. is pretty big, though for a pre-assembled unit; bigger than 2 2-car garages. Maybe a couple of sheds? Good luck.

The other suggestions are all very good. However, I would suggest that you check with you local Building Codes Office or City Hall to see if you can have such a site in your backyard. 1,000 sq. ft. is a pretty large building and may in fact be too big to put in your yard.