Thanks Jonna!
For my own seeds I had bought a box of "coin envelopes" which are paper and seem to work great. There is no static electricity and seeds come out easily. I keep them in a large closed plastic box with some desiccant, which really keeps it dry in there. Right now I could get another box of $1000 for $37, and I have a 50% off coupon, so this works out to less than 2 cents each. that is cheap enough for me. For bigger seeds or many seeds, a box of 50 regular size envelopes can be bought at the $1 store, this is also 2 cents each.
This year I joined seed swaps. For these seed swaps people seem to want/require clear plastic bags. I found some that were inexpensive, although I can't recall exactly it was more than 2 cents each. I thought plastic was requested so we could see the seeds, but I was a bit worried about sealing in moisture. I was also worried about static electricity and the seeds getting stuck in there, as seems to have happened. I was super careful to dry the seeds well. I figured if I keep the seeds I receive in plastic in my dry box it should help prevent mold, although if the seeds were still damp when placed inside it might be a lost cause. The ability to open and close with the ziplock is nice, and I do like it better than the paper coin envelopes. I think some of the seeds you are talking about were mine. Sorry!
If we put our swap seeds in a fold of paper inside the plastic ziplock bag, the seeds will not be visible. so why don't we just use the little paper "coin envelopes"? I am not being snarky at all, just trying to learn why we do things, usually there are good reasons.