I have nearly 300 Mason jars that I've accumlated over the years -- yet I still scrounge for jars at the height of canning season. A major part of it is poor stores management on my part: I don't eat some of the stuff up fast enough. At least I do keep track of what is around from the past year or two and put a priority on using that first. But there is only so much mustard and ketchup two people can eat in a year.
Of course I can give stuff away as presents, and I do, with much appreciation from recipients. But once a jar leaves this house, it rarely returns. I can only hope it is being reused. But I've reached the point, with the rising price of new jars, of not using new jars for gifts.
So I periodically check the Value Village housewares section. Four pint Mason jars, often with bands and lids, which is the size I most frequently use, can be had for a Canadian buck plus the sales tax. These are the jars I use for Christmas gifts, as it were.
Another kind of jar is the non-sealing kind. We're getting fewer and fewer of these in our house every year. Some is because food manufacturers have been moving to lighter-shipping-weight plastic for things that used to come in jars. A lot is because most things that come in jars (jams, pickles, fruit, sauces) I put up myself in my own Mason jars.
But these jars are great for such home-made gifts as body sugars, bath salts, soup mix, and spice mixes. Baking mixes are a "once opened, it's used" sort of thing and they can easily be put into cleaned and dried milk bags (4 liters of milk are often sold in a set of three bags here in Canada -- nice size for something like a cookie mix).
The source for these: the neighborhood scrounge on garbage/recycle day. Sometimes I score Mason jars as well!