Stop off at your local Nordstrom, Macy’s or Belk makeup counters. They have tons of small sample jars with screw on lids. I grabbed a dozen or so the last time I took my wife to the mall. Free is always a good price and they haven’t leaked yet. I also use them for spare pill packs in my backpack, Vaseline out of a larger jar, hand lotion, etc... I probably wouldn’t put them in a checked back to be stored under the plane but just fine for carry on.