Google "cookie jar collectors" there are lots....then ask and keep on asking.

The thing is, the lids usually get broken first. One can find jars without lids easier than they can find lids without jars through collectors. I live in the vicinity where many art potteries were located, and the pottery sales lots often have tubs of odd lids purchased when the potteries were doing their production runs. IOW extras. The availability of finding an extra lid here is much higher than anywhere else I can think of, if you know what you are looking for, and if it's a line produced locally over the years.

How old is your cookie jar? Who made that line? Where?

the line is maybe from 1950-1969 era and made by American Bisque stamped with a 739 on the bottom.