Maggot,
two or three ideas. If you can look up someplace like NASCO ; FLINN or FREY SCIENTIFIC supply companie on the internet, you can order about 50 at a time. I know that is too many, but that is one way. Another, possibly more feasible way is to visit local science or agriculture teachers at the local high school and see if they would sell you a seed specimen bottle or two. They range in size up to a Portable Aqua bottle. Any way, good luck finding what you need.