Although these coins are legal tender, they are not minted for general circulation. Each commemorative coin is produced by the U.S. Mint in limited quantity and is only available for a limited time.
The WW I Centennial Silver Dollar (90% Silver) is available from the US Mint for $51.95 (Proof) and $48.95 (Uncirculated) plus shipping until 20 February, then the price will increase to $56.95 / $53.95. There will be 350,000 produced and some of the profit will go for a WW I Memorial. The medals are available only in a two coin set (dollar plus one branch medal) for $99.95. The sets can be ordered thru 20 February
https://catalog.usmint.gov/world-war...010818&start=1
https://catalog.usmint.gov/interests...012218#start=1
The Mint has other military medals for $6.95 (1.5") and $39.95 (3").
https://catalog.usmint.gov/medals/military/