Living in New York City, we often get spoiled into thinking that we can get anything here (I know I imagined that it would be that way back when I was still scheming to get here). Surprise! There are lots of things you can get in other parts of America which are virtually inaccessible to New York City residents — We have no Walmart, and Mason/Ball jars are really hard to track down.
If you live in the rest of America, I have seen that you can pick up jars at Walmart, Kmart, and Target, as well as at hardware stores.
Ace Hardware: find a local store (most are in Manhattan), order on-line, and then pick up at the Ace Hardware that you have chosen without paying shipping (this is where I go, because there is an Ace Hardware store in the Village which is right next to a train station for the M line).
True Value will also ship free-of-charge jars you buy on-line to the local store you specify. The jar prices are competitive with Ace Hardware. There are a number of True Value stores in Manhattan.
Rainbow Ace Hardware at 1st Ave and 75th: Highly-rated canning supply section, with flats of jars in all sizes, lids, canning gadgets and utensils, as well as pectin and pickling spices. Prices said to be not bad for NYC.
Home Depot, 23rd Street: various sizes of jars, and lids. They say that, if you find a lower price elsewhere, if you talk to the Head Cashier, they will match the price. (I could not find canning jars on the Home Depot website).
Surprise Surprise, 3rd Ave and 12th St:. Carries jars at prices ranging from $1.50 – $2.99. Small discount for flats.
23rd Street Hardware, 23rd Street between 3rd and Park: good selection of jars and lids. May be willing to special order what you don’t see. This is a True Value store, so you can order on-line and have the products delivered free-of-charge. truevalue.com prices are competitive with acevalue.com prices.
Broadway Panhandler, 65 E. 8th St.: Good selection of jars you can buy by the ones, or as flats. I didn’t price them, just noticed that they are available there, and they had some unusual Bell jar styles.
PRETTY SMART RAW FOOD IDEAS 
I’ve learned to stock up during Fall canning season, because they’re much cheaper then, and easier to find. I hadn’t thought of ordering them online & picking them up at the store. Good idea! Thank you.
You are very welcome! Even things the lengths that big city people go to approximate the efforts of folks in the “rest of America” can produce positive results, and even generate new methods