|Most of these are extremely in demand nowadays. Some enthusiasts prefer to proudly showcase their coins in archival folders, while others prefer airtight capsules, or mylar-lined carboard. Whatever you choose, do not store yours in the PVC flips you frequently find on the marketplace. They are comprised of polyvinyl chloride which breaks down in time and destroys the coin it was intended to preserve. In the event you buy a coin already within one of these, move it ASAP to something better. You might consider acetate flips, but understand that these are brittle and might scuff the coin if it is not inserted and taken out carefully. While they are not air-tight, they are reasonable alternatives for moderate value coins that will be "left alone" for numerous a long time.
One thing is certain: regardless of wherever you decide to keep your coins, it'll always a source of permanent pride.