Canning salt is the same as pickling salt. It's the same thing as table salt minus the iodine, refined a little more to remove more minerals, and sans the anti-caking additives that can cause browning or clouding when using regular table salt.
I don't know where you live - so don't know if buying it in a "jar" is normal for your location or not, or how big a jar is. Here in North Texas where I live - we get pickling salt in a 2 or 4 pound bag, or box, for about $2 -$4 - depending on the store, brand, and how it's packaged.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain