I got some from the link below (scroll down the page for the plastic ones):

http://www.lifestylestore.com/ls_vials&goodies.html

The glass ones have a neck that is slightly smaller than the rest of the bottle. The plastic ones are the same inner diameter all the way down. But that's because the plastic walls are thicker than the glass walls. So the plastic i.d., while constant, is smaller than the glass i.d. The o.d. is the same for both glass and plastic vials. They have screw tops. They would easily fit in an Altoids tin PSK. I think these are too small, diameter-wise, for fishhooks and safety pins (except small specimens). They are from a prospecting supplies store - normally used to store gold samples and such. I don't know about minimum orders. Their shipping charges seem pretty high to me. I avoided that because I have one of their brick'n'morter stores near me.

Other oddball places to look are homemage perfume supply stores. Check out "perfume vials" or "perfume supplies" in a Google search. Along with "prospecting supplies". Actually, I just tried Google with "little plastic bottles" and "little plastic vials" and came up with some decent looking potential suppliers.