[dotancohen]

Or don't declare your collection. In fact, as the value of coins continues to rise, I would try to maximize (but not horde) my influx of coins, not willfully exchange them for a less-demand form of currency.

Remember, the concept of supply and demand is still valid even for currency marked with an official denomination. You could think of that marking as the _minimum_ value of the currency, as guaranteed by the state.