The primary medium of exchange (Money) for the purchase of goods and services from vendors within Middle-earth is coinage. There are three denominations of coin: Gold, Silver, and Copper.
As of Update 13, you can purchase (and redeem) "Bags of coin" from the Vault-keepers of Middle-earth. These can then be mailed, traded, or placed in your various shared storage vessels to allow the easy exchange of money between characters on your account.
For currencies used in the purchase of other goods and services from Turbine via the in-game store or various "pop-up" dialogs: