SWIM has found it stores best in plastic labelled "HDPE". In Canada, they come with little recyclable signs with the number "2" in them printed on the bottom of the container. Pill bottles (Eg ASA, Tylenol) are typically made of this kind of plastic, and if they have a good, screw on lid, tend to hold it.
If you want to go with glass, SWIM has found glass vials for sale at a hardware/gardening store. They are found in 4-20ml sizes, and typically have plastic lids, with inner plastic seals, made out of PET. These usually serve well for short term storage/distribution.
The vials are apparently for people making their own "homeopathic remedies/herbal extracts". You can find them if you look around stores that would cater to people into herbs/gardening.
