Thinking back a few generations ago our grandparents and great grandparents only had what they could grow. If you wanted to eat tomato sauce or green beans any other time besides in the summer, you had better figure out how to preserve that harvest. Not only that but you may just starve if you didn't put up enough food for your family!
Here is where I started...
The most economical way to get jars though is at garage sales. I often find the jars for less then 25 cents each and you can then buy just the lids and rings for them later. I think I have close to 800 jars at this point, but that is a good thing because during good harvest years, I fill most of them up!
But wait, I said that you didn't have to have a garden, so where do you get the produce? You can buy it at farmer's markets, the grocery store, or even apple orchards. If you are short on funds you can also glean fruits that others may not want. (post here)
When you buy your produce in bulk you save a ton of money. There is an apple orchard down the road from me where I can buy 40 pounds of apple "seconds" for $15. (that's .37 cents a pound!!!) Since we eat a lot of apples, but not that many, I do this and can applesauce to save for the later months when I can no longer get those delicious apples.
So you don't live near an apple orchard? No problem. Most grocery stores sell green beans by the pound where you can parcel out how much you want, in the height of the growing season they are often VERY inexpensive, when you take those home and can or freeze them you save a TON (NOTE: canning green beans requires a pressure canner, not hard to use but it is an additional piece of equipment to purchase. Or, if you want you can just blanch and freeze those beans (no worries the Ball book I mentioned goes through all of those steps in detail and explains it all!)
Just in case you want to go whole hog...here is the link to a pressure canner, oh and this is the cheapest time of year to buy them because during canning season the prices increase, sometimes dramatically.
There you have it, if nothing else buy or borrow the book I mentioned above and get a good look at the photos that explain everything. It really isn't as difficult as you might think and though my mom cans jams and tomatoes I taught myself about most of the other products I can, it really is that easy.