If you mean the tapered ones then it is still often cheaper to buy them, throw out the jam and use them. I have a hobby that uses them and most resorted to doing this.
Squeez do cheaper versions than the Bonne Maman jam range, and the jars are the same. Empty jars are very expensive.
Some other food jars might be suitable, ones where the food should not have imparted too much flavour on lids, like canned carrots or tomato sauce. If you soak lids in baking soda & water it can absorb out some of the tastes, or I think you could put clingfilm or some paper stuff on the lids.
Hoarde jars through the year - from anything and everything, jams, sauces, pesto, pickles, so on. THROW AWAY THE LIDS.
You can buy bags of jar lids in different standard sizes on the internet far more cheaply than buying the jars themselves - look for preserving supplies websites.