You can do canning in boiling water for high-acid foods, such as pickles and tomatoes, but you’ll need a big pressure cooker for the rest of the menu, including meats. Obviously, that makes water-bath canning a lot cheaper.
The other expense is jars and lids. Canning lids are used once and thrown away, unless you use the old-fashioned glass lids with rubber rings. Buy a lot of jars, in pint and quart sizes.
Be advised you won’t need as many replacement jars if you don’t give anything away. Seriously. If you think your Elderberry Jelly is so good that people will just love it, work on the assumption that only 20 percent of those jars will come home again. The rest are lost forever.
There are other ways to reduce cost, such as making your own pectin (needed for jellymaking) but commercial stuff is much better quality.
Here is a link to reusable canning jars lids.
I have some myself and they have worked just fine.
Tattler Reusable Canning Jar lids.
http://www.reusablecanninglids.com/
And for pectin, this stuff is THE BEST.
You can make triple batches. I use 12 C fruit and 4 C sugar and it fills 7 pints, enough for one canner load.
It's very a versatile pectin and much easier to use than Certo or Sure Jell.
Pomona's Universal Pectin