Refer to a coin collecting blue book for prices.
If you refer to the Australian One Dollar coin, the only person to feature on every coin to date is Queen Elizabeth II.
Refer to a coin collecting website.
A coin collection is called, well, a coin collection. The hobby of collecting coins is called numismatics.
a coin collector
Coin collecting
There are two basic meanings to the term "trends" in terms of coin collecting. Both relate to the resale value of a coin. #Trends can refer to the general tendency for a coin's value to increase or decrease. Value trends for gold coinage, for example, are currently (as of 6/21/2007) rising, simply because gold itself is increasing in value. Value trends for recent US Proof sets, though, are dropping. #Trends is the old name for Coin World's coin value column. Thus the phrase "Trends at $37,000" would mean that the value according to "Coin World Trends" has been around $37,000. Recently the column has changed to Coin World Values and has spun off into its own publication.
While the president has not said much about coin collecting, he has said a lot about education and about the importance of hobbies that are educational. Both stamp collecting and coin collecting teach about geography and about important historical figures, so the chances are, he would be in favor of such hobbies.
Coin collecting
Numismatology
If you refer to the collector value, any value would depend on the country of issue, the date and the condition of the coin.
Lots of wear on the coin and the lowest grading possible.