It has been awhile since I bought any I got something like 300 different types. If I remember the place or find it I will let you know. One thing to remember is you want acid free baggies I have had mine in the same bags for 3 years now at least as well as silver coins and other coins.
Some recommend you put a hole in as a vent, for mine some do have a hole and some don't I haven't really noticed any difference. But that may also depend on where you are storing them as well mine are away from direct sunlight and where the temp and humidity are pretty constant.
Hopefully others will chime in and they may even use the same place as me to get them so it could be a bonus for us both