I wouldn't worry too much - it's probably that we're just hitting the beginning of peak demand for canning supplies (everyone's gardens are starting to produce). On top of that, my wife & I have both noticed that Wal-Mart & other stores are stocking less canning supplies in general, and they aren't stocking them year-round - probably because fewer and fewer people are canning nowadays (I remember my Mom & most of my friend's mothers canning every year when I was a kid, but I am the only person I know among my friends & co-workers who is doing any canning).
Places I've had luck finding jars:
Big Lots - this is where I bought the bulk of my new jars this year. $2 cheaper per dozen than Wally World.
Farm-oriented / hardware stores - TSC, The Andersons, etc.. We picked up some small jelly jars at The Andersons last weekend, and they had all their canners & jars on sale, displayed right at the front entrance of the store. I think I've seen canning supplies at some hardware stores (ACE Hardware, maybe? They closed our local ACE, so I'm not sure...)
Craigslist - search for "canning" or "mason jars". Most of the ads I saw were too expensive, IMHO (most people were asking $5/dozen for jars only, vs. $7/dozen for new jars w/ lids & bands). But, if you need jars RIGHT NOW, I guess it's better than nothing.
Salvation Army / thrift stores - can be hit-or-miss, but I've seen at least a dozen or so jars at every one I've been to. There are 4 or 5 thrift stores within 20 minutes of my house, so I could scrounge up 50 or so jars pretty quick with $20 and an afternoon of driving.
Garage sales - Obviously, these are the most hit-or-miss. Check the ads on Craigslist and in your local paper to see if they mention "canning supplies". If you have friends or family members who hit a lot of garage sales, put the word out to them that you'll reimburse them + a couple of bucks for their trouble if they pick up any jars they see at xxx
price. It can take a while, but sometimes you can get a big score:
...as I mentioned earlier tonight in the canning thread
, we got 100 jars for ten cents apiece.
This was because one of my wife's co-workers is a garage sale fanatic, and asked us if we wanted her to be on the lookout for anything - we told her "canning jars", and she said "How much do you want to pay?" We told her "25 cents apiece or less". She called today and said "Come pick up your jars - you might wanna empty your trunk first..."