The benefits, as mentioned, can be as simple as knowing what's inside your food, economy,taste and lots of reasons in between. Canning, in general, is usually cheaper in the long run than buying can as well as more nutritious. If you get your canning supplies on sale and watch your bottom line when buying your food you can create meals as low as $1 a person. My friend and I just spent the day canning chili and it comes out to about 40 cents a pint.
A canned item usually lasts between 1 to 5 years, depending on the ingredients. The jars and canning band is reusable, but the lids generally aren't. The majority of lids have the sealing compound on the lid itself and only allows for one seal, so you'll have to buy new lids when you run out or can for the next year but jars, bands and lids usually stay well in storage so you can stock up when cheap and keep them until the next season. The good news is Tattler Lids allow for reuse though I hear they're a bit pricey.
The first things to consider would be how much you were planning on canning and therefore what size capacity canner you need and whether you'd like water bath, pressure canner or both. Water bath canning is good for high acid food canning and pressure canner for low acid or high acid canning. I went for a pressure canner simply because I wanted to pay once for an all-around workhorse instead of relying on two different canners ( though I did buy a speckled graniteware waterbath canner on the cheap because it was cheaper than the regular cooking kettles and was the same thing).
My pressure canner is a Presto 23 quart from amazon.com that was $75. My cans were on sale and cost $2.50 a case and the basic canning tools cost me just under $7. To keep prices low I buy in bulk when produce is in season and ask produce dept managers if there's a price break for buying by the crate/box worth. Lots are open to drop it a few cents a pound which really adds up. Managed to get a 40 pound box of bananas for only $4 the other day and the only problem was they were a shade overripe, but perfect for banana butter and banana bread.
I'd really recommend the Presto and ball/kerr websites. They usually have lots of info and the occasional instructional video. Youtube is also great and I love Beaxarprepper, I think her name is. Kerr/Ball also puts out a basic book on beginning canning but they also have a nice, thick book of om nom nommy goodness called The Complete Canning Guide. Lots of info and recipes to get you started.