A coin purse is a small bag that has a closure across the top that is meant to hold coins. Sometimes a coin purse is called a change purse. It was very popular and has lost some of it popularity over the years. It has become something of a relic. It may be that they movement toward using plastic has made the coin purse all but obsolete.
A coin purse is relatively inexpensive even the top of the line designers produce an affordable coin purse. They make a great gift, especially if someone is very fond of a designer but the designer's hand bags are out of price range. It is a nice token of the designer's line.