You can buy currency sleeves that are plastic (noncorrosive?) an come in various sizes and thicknesses. Most of the currency I have is cheap and is kept in envelopes. The more expensive stuff is in a Dansco brand currency binder. I love Dansco currency binders but Dansco has been having a real issue with keeping up with demand. I have placed several orders with valley-coins.com that have had to be cancelled because Dansco just hasn't filled their orders. Other places sell them too, just not at such a good price.