ISO single serve formula powder packets- ideas

Hi!

Soon to have my third baby- with my second someone bought me these amazing single serve formula packets- they were powder and made a 4 ounce bottle. About 20 came in a box. Perfect for supplementing for a breastfeeding mom who needs occasional help but could not use up a whole big container in the time frame.

This time, I cannot find them- not online (Amazon let me down) nor in stores. Has anyone seen these? Any ideas where I could buy some? They bring so much peace of mind. Thanks in advance!